* [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out [not found] <20170406053515.4842-1-ying.huang@intel.com> @ 2017-04-06 5:35 ` Huang, Ying 2017-04-14 14:58 ` Johannes Weiner 0 siblings, 1 reply; 5+ messages in thread From: Huang, Ying @ 2017-04-06 5:35 UTC (permalink / raw) To: Andrew Morton Cc: linux-mm, linux-kernel, Huang Ying, Andrea Arcangeli, Ebru Akagunduz, Johannes Weiner, Michal Hocko, Tejun Heo, Hugh Dickins, Shaohua Li, Minchan Kim, Rik van Riel, cgroups From: Huang Ying <ying.huang@intel.com> In this patch, splitting huge page is delayed from almost the first step of swapping out to after allocating the swap space for the THP (Transparent Huge Page) and adding the THP into the swap cache. This will batch the corresponding operation, thus improve THP swap out throughput. This is the first step for the THP swap optimization. The plan is to delay splitting the THP step by step and avoid splitting the THP finally. The advantages of the THP swap support include: - Batch the swap operations for the THP and reduce lock acquiring/releasing, including allocating/freeing the swap space, adding/deleting to/from the swap cache, and writing/reading the swap space, etc. This will help to improve the THP swap performance. - The THP swap space read/write will be 2M sequential IO. It is particularly helpful for the swap read, which usually are 4k random IO. This will help to improve the THP swap performance. - It will help the memory fragmentation, especially when the THP is heavily used by the applications. The 2M continuous pages will be free up after the THP swapping out. - It will improve the THP utilization on the system with the swap turned on. Because the speed for khugepaged to collapse the normal pages into the THP is quite slow. After the THP is split during the swapping out, it will take quite long time for the normal pages to collapse back into the THP after being swapped in. The high THP utilization helps the efficiency of the page based memory management too. There are some concerns regarding THP swap in, mainly because possible enlarged read/write IO size (for swap in/out) may put more overhead on the storage device. To deal with that, the THP swap in should be turned on only when necessary. For example, it can be selected via "always/never/madvise" logic, to be turned on globally, turned off globally, or turned on only for VMA with MADV_HUGEPAGE, etc. In this patch, one swap cluster is used to hold the contents of each THP swapped out. So, the size of the swap cluster is changed to that of the THP (Transparent Huge Page) on x86_64 architecture (512). For other architectures which want such THP swap optimization, ARCH_USES_THP_SWAP_CLUSTER needs to be selected in the Kconfig file for the architecture. In effect, this will enlarge swap cluster size by 2 times on x86_64. Which may make it harder to find a free cluster when the swap space becomes fragmented. So that, this may reduce the continuous swap space allocation and sequential write in theory. The performance test in 0day shows no regressions caused by this. In the future of THP swap optimization, some information of the swapped out THP (such as compound map count) will be recorded in the swap_cluster_info data structure. The mem cgroup swap accounting functions are enhanced to support charge or uncharge a swap cluster backing a THP as a whole. The swap cluster allocate/free functions are added to allocate/free a swap cluster for a THP. A fair simple algorithm is used for swap cluster allocation, that is, only the first swap device in priority list will be tried to allocate the swap cluster. The function will fail if the trying is not successful, and the caller will fallback to allocate a single swap slot instead. This works good enough for normal cases. If the difference of the number of the free swap clusters among multiple swap devices is significant, it is possible that some THPs are split earlier than necessary. For example, this could be caused by big size difference among multiple swap devices. The swap cache functions is enhanced to support add/delete THP to/from the swap cache as a set of (HPAGE_PMD_NR) sub-pages. This may be enhanced in the future with multi-order radix tree. But because we will split the THP soon during swapping out, that optimization doesn't make much sense for this first step. The THP splitting functions are enhanced to support to split THP in swap cache during swapping out. The page lock will be held during allocating the swap cluster, adding the THP into the swap cache and splitting the THP. So in the code path other than swapping out, if the THP need to be split, the PageSwapCache(THP) will be always false. With the patchset, the swap out throughput improves 14.9% (from about 3.77GB/s to about 4.34GB/s) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. The detailed comparison result is as follow, base base+patchset ---------------- -------------------------- %stddev %change %stddev \ | \ 7043990 ± 0% +21.2% 8536807 ± 0% vm-scalability.throughput 109.94 ± 1% -16.2% 92.09 ± 0% vm-scalability.time.elapsed_time 3957091 ± 0% +14.9% 4547173 ± 0% vmstat.swap.so 31.46 ± 1% -38.3% 19.42 ± 0% perf-stat.cache-miss-rate% 1.04 ± 1% +22.2% 1.27 ± 0% perf-stat.ipc 9.33 ± 2% -60.7% 3.67 ± 1% perf-profile.calltrace.cycles-pp.add_to_swap.shrink_page_list.shrink_inactive_list.shrink_node_memcg.shrink_node The swap cluster is only available for SSD, so the THP swap optimization in this patchset has no effect for HDD. Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: cgroups@vger.kernel.org Suggested-by: Andrew Morton <akpm@linux-foundation.org> [for config option] Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> [for changes in huge_memory.c and huge_mm.h] --- arch/x86/Kconfig | 1 + include/linux/page-flags.h | 5 +- include/linux/swap.h | 37 ++++-- include/linux/swap_cgroup.h | 6 +- mm/Kconfig | 13 +++ mm/huge_memory.c | 11 +- mm/memcontrol.c | 58 ++++++---- mm/shmem.c | 6 +- mm/swap_cgroup.c | 40 +++++-- mm/swap_slots.c | 7 +- mm/swap_state.c | 125 +++++++++++++------- mm/swapfile.c | 275 ++++++++++++++++++++++++++++++++------------ mm/vmscan.c | 2 +- 13 files changed, 413 insertions(+), 173 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 9a5af1e1cd61..7300c2f6bf13 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -178,6 +178,7 @@ config X86 select USER_STACKTRACE_SUPPORT select VIRT_TO_BUS select X86_FEATURE_NAMES if PROC_FS + select ARCH_USES_THP_SWAP_CLUSTER if X86_64 config INSTRUCTION_DECODER def_bool y diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 6b5818d6de32..f4acd6c4f808 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -326,11 +326,12 @@ PAGEFLAG_FALSE(HighMem) #ifdef CONFIG_SWAP static __always_inline int PageSwapCache(struct page *page) { + page = compound_head(page); return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); } -SETPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) -CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) +SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) +CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) #else PAGEFLAG_FALSE(SwapCache) #endif diff --git a/include/linux/swap.h b/include/linux/swap.h index 486494e6b2fc..9295b583c268 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -386,15 +386,15 @@ static inline long get_nr_swap_pages(void) } extern void si_swapinfo(struct sysinfo *); -extern swp_entry_t get_swap_page(void); +extern swp_entry_t __get_swap_page(void); extern swp_entry_t get_swap_page_of_type(int); -extern int get_swap_pages(int n, swp_entry_t swp_entries[]); +extern int get_swap_pages(int n, swp_entry_t swp_entries[], bool huge); extern int add_swap_count_continuation(swp_entry_t, gfp_t); extern void swap_shmem_alloc(swp_entry_t); extern int swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern void swap_free(swp_entry_t); -extern void swapcache_free(swp_entry_t); +extern void swapcache_free(swp_entry_t entry, bool huge); extern void swapcache_free_entries(swp_entry_t *entries, int n); extern int free_swap_and_cache(swp_entry_t); extern int swap_type_of(dev_t, sector_t, struct block_device **); @@ -456,7 +456,7 @@ static inline void swap_free(swp_entry_t swp) { } -static inline void swapcache_free(swp_entry_t swp) +static inline void swapcache_free(swp_entry_t swp, bool huge) { } @@ -518,7 +518,7 @@ static inline int try_to_free_swap(struct page *page) return 0; } -static inline swp_entry_t get_swap_page(void) +static inline swp_entry_t __get_swap_page(void) { swp_entry_t entry; entry.val = 0; @@ -527,6 +527,21 @@ static inline swp_entry_t get_swap_page(void) #endif /* CONFIG_SWAP */ +static inline swp_entry_t get_swap_page(bool huge) +{ +#ifdef CONFIG_THP_SWAP_CLUSTER + if (huge) { + swp_entry_t entry; + + if (get_swap_pages(1, &entry, true)) + return entry; + else + return (swp_entry_t) {0}; + } else +#endif + return __get_swap_page(); +} + #ifdef CONFIG_MEMCG static inline int mem_cgroup_swappiness(struct mem_cgroup *memcg) { @@ -550,8 +565,10 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) #ifdef CONFIG_MEMCG_SWAP extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); -extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); -extern void mem_cgroup_uncharge_swap(swp_entry_t entry); +extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry, + bool compound); +extern void mem_cgroup_uncharge_swap(swp_entry_t entry, + unsigned int nr_entries); extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); extern bool mem_cgroup_swap_full(struct page *page); #else @@ -560,12 +577,14 @@ static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry) } static inline int mem_cgroup_try_charge_swap(struct page *page, - swp_entry_t entry) + swp_entry_t entry, + bool compound) { return 0; } -static inline void mem_cgroup_uncharge_swap(swp_entry_t entry) +static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, + unsigned int nr_entries) { } diff --git a/include/linux/swap_cgroup.h b/include/linux/swap_cgroup.h index 145306bdc92f..b2b8ec7bda3f 100644 --- a/include/linux/swap_cgroup.h +++ b/include/linux/swap_cgroup.h @@ -7,7 +7,8 @@ extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, unsigned short old, unsigned short new); -extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id); +extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id, + unsigned int nr_ents); extern unsigned short lookup_swap_cgroup_id(swp_entry_t ent); extern int swap_cgroup_swapon(int type, unsigned long max_pages); extern void swap_cgroup_swapoff(int type); @@ -15,7 +16,8 @@ extern void swap_cgroup_swapoff(int type); #else static inline -unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) +unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id, + unsigned int nr_ents) { return 0; } diff --git a/mm/Kconfig b/mm/Kconfig index c89f472b658c..3edfa6a4bf67 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -499,6 +499,19 @@ config FRONTSWAP If unsure, say Y to enable frontswap. +config ARCH_USES_THP_SWAP_CLUSTER + bool + default n + +config THP_SWAP_CLUSTER + bool + depends on SWAP && TRANSPARENT_HUGEPAGE && ARCH_USES_THP_SWAP_CLUSTER + default y + help + Use one swap cluster to hold the contents of the THP + (Transparent Huge Page) swapped out. The size of the swap + cluster will be same as that of THP. + config CMA bool "Contiguous Memory Allocator" depends on HAVE_MEMBLOCK && MMU diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d14dd961f626..4a5c1ca21894 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2185,7 +2185,7 @@ static void __split_huge_page_tail(struct page *head, int tail, * atomic_set() here would be safe on all archs (and not only on x86), * it's safer to use atomic_inc()/atomic_add(). */ - if (PageAnon(head)) { + if (PageAnon(head) && !PageSwapCache(head)) { page_ref_inc(page_tail); } else { /* Additional pin to radix tree */ @@ -2196,6 +2196,7 @@ static void __split_huge_page_tail(struct page *head, int tail, page_tail->flags |= (head->flags & ((1L << PG_referenced) | (1L << PG_swapbacked) | + (1L << PG_swapcache) | (1L << PG_mlocked) | (1L << PG_uptodate) | (1L << PG_active) | @@ -2258,7 +2259,11 @@ static void __split_huge_page(struct page *page, struct list_head *list, ClearPageCompound(head); /* See comment in __split_huge_page_tail() */ if (PageAnon(head)) { - page_ref_inc(head); + /* Additional pin to radix tree of swap cache */ + if (PageSwapCache(head)) + page_ref_add(head, 2); + else + page_ref_inc(head); } else { /* Additional pin to radix tree */ page_ref_add(head, 2); @@ -2414,7 +2419,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) ret = -EBUSY; goto out; } - extra_pins = 0; + extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; mapping = NULL; anon_vma_lock_write(anon_vma); } else { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 490d5b4676c1..6987c6e91b35 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2393,10 +2393,9 @@ void mem_cgroup_split_huge_fixup(struct page *head) #ifdef CONFIG_MEMCG_SWAP static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg, - bool charge) + int nr_entries) { - int val = (charge) ? 1 : -1; - this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val); + this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], nr_entries); } /** @@ -2422,8 +2421,8 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry, new_id = mem_cgroup_id(to); if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { - mem_cgroup_swap_statistics(from, false); - mem_cgroup_swap_statistics(to, true); + mem_cgroup_swap_statistics(from, -1); + mem_cgroup_swap_statistics(to, 1); return 0; } return -EINVAL; @@ -5451,7 +5450,7 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg, * let's not wait for it. The page already received a * memory+swap charge, drop the swap entry duplicate. */ - mem_cgroup_uncharge_swap(entry); + mem_cgroup_uncharge_swap(entry, nr_pages); } } @@ -5879,9 +5878,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) * ancestor for the swap instead and transfer the memory+swap charge. */ swap_memcg = mem_cgroup_id_get_online(memcg); - oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg)); + oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg), 1); VM_BUG_ON_PAGE(oldid, page); - mem_cgroup_swap_statistics(swap_memcg, true); + mem_cgroup_swap_statistics(swap_memcg, 1); page->mem_cgroup = NULL; @@ -5908,19 +5907,23 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) css_put(&memcg->css); } -/* - * mem_cgroup_try_charge_swap - try charging a swap entry +/** + * mem_cgroup_try_charge_swap - try charging a set of swap entries * @page: page being added to swap - * @entry: swap entry to charge + * @entry: the first swap entry to charge + * @compound: charge the swap entries as compound or small swap entry * - * Try to charge @entry to the memcg that @page belongs to. + * Try to charge a set of swap entries starting from @entry to the + * memcg that @page belongs to. * * Returns 0 on success, -ENOMEM on failure. */ -int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) +int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry, + bool compound) { struct mem_cgroup *memcg; struct page_counter *counter; + unsigned int nr_entries = compound ? hpage_nr_pages(page) : 1; unsigned short oldid; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account) @@ -5935,25 +5938,29 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) memcg = mem_cgroup_id_get_online(memcg); if (!mem_cgroup_is_root(memcg) && - !page_counter_try_charge(&memcg->swap, 1, &counter)) { + !page_counter_try_charge(&memcg->swap, nr_entries, &counter)) { mem_cgroup_id_put(memcg); return -ENOMEM; } - oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg)); + if (nr_entries > 1) + mem_cgroup_id_get_many(memcg, nr_entries - 1); + oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_entries); VM_BUG_ON_PAGE(oldid, page); - mem_cgroup_swap_statistics(memcg, true); + mem_cgroup_swap_statistics(memcg, nr_entries); return 0; } /** - * mem_cgroup_uncharge_swap - uncharge a swap entry - * @entry: swap entry to uncharge + * mem_cgroup_uncharge_swap - uncharge a set of swap entries + * @entry: the first swap entry to uncharge + * @nr_entries: the number of swap entries to uncharge * - * Drop the swap charge associated with @entry. + * Drop the swap charge associated with @nr_entries swap entries + * starting from @entry. */ -void mem_cgroup_uncharge_swap(swp_entry_t entry) +void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_entries) { struct mem_cgroup *memcg; unsigned short id; @@ -5961,18 +5968,19 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry) if (!do_swap_account) return; - id = swap_cgroup_record(entry, 0); + id = swap_cgroup_record(entry, 0, nr_entries); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (memcg) { if (!mem_cgroup_is_root(memcg)) { if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) - page_counter_uncharge(&memcg->swap, 1); + page_counter_uncharge(&memcg->swap, nr_entries); else - page_counter_uncharge(&memcg->memsw, 1); + page_counter_uncharge(&memcg->memsw, + nr_entries); } - mem_cgroup_swap_statistics(memcg, false); - mem_cgroup_id_put(memcg); + mem_cgroup_swap_statistics(memcg, -nr_entries); + mem_cgroup_id_put_many(memcg, nr_entries); } rcu_read_unlock(); } diff --git a/mm/shmem.c b/mm/shmem.c index e67d6ba4e98e..2d7414241f71 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1290,11 +1290,11 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) SetPageUptodate(page); } - swap = get_swap_page(); + swap = get_swap_page(false); if (!swap.val) goto redirty; - if (mem_cgroup_try_charge_swap(page, swap)) + if (mem_cgroup_try_charge_swap(page, swap, false)) goto free_swap; /* @@ -1326,7 +1326,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) mutex_unlock(&shmem_swaplist_mutex); free_swap: - swapcache_free(swap); + swapcache_free(swap, false); redirty: set_page_dirty(page); if (wbc->for_reclaim) diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c index 310ac0b8f974..8cee2d125815 100644 --- a/mm/swap_cgroup.c +++ b/mm/swap_cgroup.c @@ -58,21 +58,27 @@ static int swap_cgroup_prepare(int type) return -ENOMEM; } +static struct swap_cgroup *__lookup_swap_cgroup(struct swap_cgroup_ctrl *ctrl, + pgoff_t offset) +{ + struct page *mappage; + struct swap_cgroup *sc; + + mappage = ctrl->map[offset / SC_PER_PAGE]; + sc = page_address(mappage); + return sc + offset % SC_PER_PAGE; +} + static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent, struct swap_cgroup_ctrl **ctrlp) { pgoff_t offset = swp_offset(ent); struct swap_cgroup_ctrl *ctrl; - struct page *mappage; - struct swap_cgroup *sc; ctrl = &swap_cgroup_ctrl[swp_type(ent)]; if (ctrlp) *ctrlp = ctrl; - - mappage = ctrl->map[offset / SC_PER_PAGE]; - sc = page_address(mappage); - return sc + offset % SC_PER_PAGE; + return __lookup_swap_cgroup(ctrl, offset); } /** @@ -105,25 +111,39 @@ unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, } /** - * swap_cgroup_record - record mem_cgroup for this swp_entry. - * @ent: swap entry to be recorded into + * swap_cgroup_record - record mem_cgroup for a set of swap entries + * @ent: the first swap entry to be recorded into * @id: mem_cgroup to be recorded + * @nr_ents: number of swap entries to be recorded * * Returns old value at success, 0 at failure. * (Of course, old value can be 0.) */ -unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) +unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id, + unsigned int nr_ents) { struct swap_cgroup_ctrl *ctrl; struct swap_cgroup *sc; unsigned short old; unsigned long flags; + pgoff_t offset = swp_offset(ent); + pgoff_t end = offset + nr_ents; sc = lookup_swap_cgroup(ent, &ctrl); spin_lock_irqsave(&ctrl->lock, flags); old = sc->id; - sc->id = id; + for (;;) { + VM_BUG_ON(sc->id != old); + sc->id = id; + offset++; + if (offset == end) + break; + if (offset % SC_PER_PAGE) + sc++; + else + sc = __lookup_swap_cgroup(ctrl, offset); + } spin_unlock_irqrestore(&ctrl->lock, flags); return old; diff --git a/mm/swap_slots.c b/mm/swap_slots.c index aa1c415f4abd..093570d46b09 100644 --- a/mm/swap_slots.c +++ b/mm/swap_slots.c @@ -260,7 +260,8 @@ static int refill_swap_slots_cache(struct swap_slots_cache *cache) cache->cur = 0; if (swap_slot_cache_active) - cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, cache->slots); + cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, cache->slots, + false); return cache->nr; } @@ -298,7 +299,7 @@ int free_swap_slot(swp_entry_t entry) return 0; } -swp_entry_t get_swap_page(void) +swp_entry_t __get_swap_page(void) { swp_entry_t entry, *pentry; struct swap_slots_cache *cache; @@ -334,7 +335,7 @@ swp_entry_t get_swap_page(void) return entry; } - get_swap_pages(1, &entry); + get_swap_pages(1, &entry, false); return entry; } diff --git a/mm/swap_state.c b/mm/swap_state.c index 7bfb9bd1ca21..7659557351cf 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -19,6 +19,7 @@ #include <linux/migrate.h> #include <linux/vmalloc.h> #include <linux/swap_slots.h> +#include <linux/huge_mm.h> #include <asm/pgtable.h> @@ -38,6 +39,7 @@ struct address_space *swapper_spaces[MAX_SWAPFILES]; static unsigned int nr_swapper_spaces[MAX_SWAPFILES]; #define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0) +#define ADD_CACHE_INFO(x, nr) do { swap_cache_info.x += (nr); } while (0) static struct { unsigned long add_total; @@ -90,39 +92,52 @@ void show_swap_cache_info(void) */ int __add_to_swap_cache(struct page *page, swp_entry_t entry) { - int error; + int error, i, nr = hpage_nr_pages(page); struct address_space *address_space; + struct page *cur_page; + swp_entry_t cur_entry; VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageSwapCache(page), page); VM_BUG_ON_PAGE(!PageSwapBacked(page), page); - get_page(page); + page_ref_add(page, nr); SetPageSwapCache(page); - set_page_private(page, entry.val); address_space = swap_address_space(entry); + cur_page = page; + cur_entry.val = entry.val; spin_lock_irq(&address_space->tree_lock); - error = radix_tree_insert(&address_space->page_tree, - swp_offset(entry), page); - if (likely(!error)) { - address_space->nrpages++; - __inc_node_page_state(page, NR_FILE_PAGES); - INC_CACHE_INFO(add_total); + for (i = 0; i < nr; i++, cur_page++, cur_entry.val++) { + set_page_private(cur_page, cur_entry.val); + error = radix_tree_insert(&address_space->page_tree, + swp_offset(cur_entry), cur_page); + if (unlikely(error)) + break; } - spin_unlock_irq(&address_space->tree_lock); - - if (unlikely(error)) { + if (likely(!error)) { + address_space->nrpages += nr; + __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr); + ADD_CACHE_INFO(add_total, nr); + } else { /* * Only the context which have set SWAP_HAS_CACHE flag * would call add_to_swap_cache(). * So add_to_swap_cache() doesn't returns -EEXIST. */ VM_BUG_ON(error == -EEXIST); - set_page_private(page, 0UL); + set_page_private(cur_page, 0UL); + while (i--) { + cur_page--; + cur_entry.val--; + radix_tree_delete(&address_space->page_tree, + swp_offset(cur_entry)); + set_page_private(cur_page, 0UL); + } ClearPageSwapCache(page); - put_page(page); + page_ref_sub(page, nr); } + spin_unlock_irq(&address_space->tree_lock); return error; } @@ -132,7 +147,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) { int error; - error = radix_tree_maybe_preload(gfp_mask); + error = radix_tree_maybe_preload_order(gfp_mask, compound_order(page)); if (!error) { error = __add_to_swap_cache(page, entry); radix_tree_preload_end(); @@ -148,6 +163,7 @@ void __delete_from_swap_cache(struct page *page) { swp_entry_t entry; struct address_space *address_space; + int i, nr = hpage_nr_pages(page); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageSwapCache(page), page); @@ -155,12 +171,17 @@ void __delete_from_swap_cache(struct page *page) entry.val = page_private(page); address_space = swap_address_space(entry); - radix_tree_delete(&address_space->page_tree, swp_offset(entry)); - set_page_private(page, 0); + for (i = 0; i < nr; i++, entry.val++) { + struct page *cur_page = page + i; + + radix_tree_delete(&address_space->page_tree, + swp_offset(entry)); + set_page_private(cur_page, 0); + } ClearPageSwapCache(page); - address_space->nrpages--; - __dec_node_page_state(page, NR_FILE_PAGES); - INC_CACHE_INFO(del_total); + address_space->nrpages -= nr; + __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr); + ADD_CACHE_INFO(del_total, nr); } /** @@ -168,30 +189,31 @@ void __delete_from_swap_cache(struct page *page) * @page: page we want to move to swap * * Allocate swap space for the page and add the page to the - * swap cache. Caller needs to hold the page lock. + * swap cache. Caller needs to hold the page lock. */ int add_to_swap(struct page *page, struct list_head *list) { swp_entry_t entry; int err; + bool huge = false; VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageUptodate(page), page); - entry = get_swap_page(); - if (!entry.val) - return 0; +#ifdef CONFIG_THP_SWAP_CLUSTER + huge = PageTransHuge(page); +#endif - if (mem_cgroup_try_charge_swap(page, entry)) { - swapcache_free(entry); - return 0; - } +retry: + entry = get_swap_page(huge); + if (!entry.val) + goto fail; + if (mem_cgroup_try_charge_swap(page, entry, huge)) + goto free_fail; - if (unlikely(PageTransHuge(page))) - if (unlikely(split_huge_page_to_list(page, list))) { - swapcache_free(entry); - return 0; - } + if (unlikely(PageTransHuge(page)) && !huge) + if (unlikely(split_huge_page_to_list(page, list))) + goto free_fail; /* * Radix-tree node allocations from PF_MEMALLOC contexts could @@ -206,17 +228,32 @@ int add_to_swap(struct page *page, struct list_head *list) */ err = add_to_swap_cache(page, entry, __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN); - - if (!err) { - return 1; - } else { /* -ENOMEM radix-tree allocation failure */ + /* -ENOMEM radix-tree allocation failure */ + if (err) /* * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry); - return 0; + goto free_fail; + + if (unlikely(PageTransHuge(page)) && huge) { + err = split_huge_page_to_list(page, list); + if (err) { + delete_from_swap_cache(page); + return 0; + } } + + return 1; + +free_fail: + swapcache_free(entry, huge); +fail: + if (huge) { + huge = false; + goto retry; + } else + return 0; } /* @@ -237,8 +274,8 @@ void delete_from_swap_cache(struct page *page) __delete_from_swap_cache(page); spin_unlock_irq(&address_space->tree_lock); - swapcache_free(entry); - put_page(page); + swapcache_free(entry, PageTransHuge(page)); + page_ref_sub(page, hpage_nr_pages(page)); } /* @@ -295,7 +332,7 @@ struct page * lookup_swap_cache(swp_entry_t entry) page = find_get_page(swap_address_space(entry), swp_offset(entry)); - if (page) { + if (page && likely(!PageTransCompound(page))) { INC_CACHE_INFO(find_success); if (TestClearPageReadahead(page)) atomic_inc(&swapin_readahead_hits); @@ -389,7 +426,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask, * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry); + swapcache_free(entry, false); } while (err != -ENOMEM); if (new_page) @@ -506,7 +543,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, gfp_mask, vma, addr); if (!page) continue; - if (offset != entry_offset) + if (offset != entry_offset && likely(!PageTransCompound(page))) SetPageReadahead(page); put_page(page); } diff --git a/mm/swapfile.c b/mm/swapfile.c index 53b5881ee0d6..a3660a206727 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -199,7 +199,11 @@ static void discard_swap_cluster(struct swap_info_struct *si, } } +#ifdef CONFIG_THP_SWAP_CLUSTER +#define SWAPFILE_CLUSTER HPAGE_PMD_NR +#else #define SWAPFILE_CLUSTER 256 +#endif #define LATENCY_LIMIT 256 static inline void cluster_set_flag(struct swap_cluster_info *info, @@ -374,6 +378,14 @@ static void swap_cluster_schedule_discard(struct swap_info_struct *si, schedule_work(&si->discard_work); } +static void __free_cluster(struct swap_info_struct *si, unsigned long idx) +{ + struct swap_cluster_info *ci = si->cluster_info; + + cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); + cluster_list_add_tail(&si->free_clusters, ci, idx); +} + /* * Doing discard actually. After a cluster discard is finished, the cluster * will be added to free cluster list. caller should hold si->lock. @@ -394,10 +406,7 @@ static void swap_do_scheduled_discard(struct swap_info_struct *si) spin_lock(&si->lock); ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); - cluster_set_flag(ci, CLUSTER_FLAG_FREE); - unlock_cluster(ci); - cluster_list_add_tail(&si->free_clusters, info, idx); - ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); + __free_cluster(si, idx); memset(si->swap_map + idx * SWAPFILE_CLUSTER, 0, SWAPFILE_CLUSTER); unlock_cluster(ci); @@ -415,6 +424,34 @@ static void swap_discard_work(struct work_struct *work) spin_unlock(&si->lock); } +static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) +{ + struct swap_cluster_info *ci = si->cluster_info; + + VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); + cluster_list_del_first(&si->free_clusters, ci); + cluster_set_count_flag(ci + idx, 0, 0); +} + +static void free_cluster(struct swap_info_struct *si, unsigned long idx) +{ + struct swap_cluster_info *ci = si->cluster_info + idx; + + VM_BUG_ON(cluster_count(ci) != 0); + /* + * If the swap is discardable, prepare discard the cluster + * instead of free it immediately. The cluster will be freed + * after discard. + */ + if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == + (SWP_WRITEOK | SWP_PAGE_DISCARD)) { + swap_cluster_schedule_discard(si, idx); + return; + } + + __free_cluster(si, idx); +} + /* * The cluster corresponding to page_nr will be used. The cluster will be * removed from free cluster list and its usage counter will be increased. @@ -426,11 +463,8 @@ static void inc_cluster_info_page(struct swap_info_struct *p, if (!cluster_info) return; - if (cluster_is_free(&cluster_info[idx])) { - VM_BUG_ON(cluster_list_first(&p->free_clusters) != idx); - cluster_list_del_first(&p->free_clusters, cluster_info); - cluster_set_count_flag(&cluster_info[idx], 0, 0); - } + if (cluster_is_free(&cluster_info[idx])) + alloc_cluster(p, idx); VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); cluster_set_count(&cluster_info[idx], @@ -454,21 +488,8 @@ static void dec_cluster_info_page(struct swap_info_struct *p, cluster_set_count(&cluster_info[idx], cluster_count(&cluster_info[idx]) - 1); - if (cluster_count(&cluster_info[idx]) == 0) { - /* - * If the swap is discardable, prepare discard the cluster - * instead of free it immediately. The cluster will be freed - * after discard. - */ - if ((p->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == - (SWP_WRITEOK | SWP_PAGE_DISCARD)) { - swap_cluster_schedule_discard(p, idx); - return; - } - - cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); - cluster_list_add_tail(&p->free_clusters, cluster_info, idx); - } + if (cluster_count(&cluster_info[idx]) == 0) + free_cluster(p, idx); } /* @@ -558,6 +579,71 @@ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, return found_free; } +#ifdef CONFIG_THP_SWAP_CLUSTER +static inline unsigned int huge_cluster_nr_entries(bool huge) +{ + return huge ? SWAPFILE_CLUSTER : 1; +} +#else +#define huge_cluster_nr_entries(huge) 1 +#endif + +static void _swap_entry_alloc(struct swap_info_struct *si, + unsigned long offset, bool huge) +{ + unsigned int nr_entries = huge_cluster_nr_entries(huge); + unsigned int end = offset + nr_entries - 1; + + if (offset == si->lowest_bit) + si->lowest_bit += nr_entries; + if (end == si->highest_bit) + si->highest_bit -= nr_entries; + si->inuse_pages += nr_entries; + if (si->inuse_pages == si->pages) { + si->lowest_bit = si->max; + si->highest_bit = 0; + spin_lock(&swap_avail_lock); + plist_del(&si->avail_list, &swap_avail_head); + spin_unlock(&swap_avail_lock); + } +} + +static void _swap_entry_free(struct swap_info_struct *si, unsigned long offset, + bool huge) +{ + unsigned int nr_entries = huge_cluster_nr_entries(huge); + unsigned long end = offset + nr_entries - 1; + void (*swap_slot_free_notify)(struct block_device *, unsigned long); + + if (offset < si->lowest_bit) + si->lowest_bit = offset; + if (end > si->highest_bit) { + bool was_full = !si->highest_bit; + + si->highest_bit = end; + if (was_full && (si->flags & SWP_WRITEOK)) { + spin_lock(&swap_avail_lock); + WARN_ON(!plist_node_empty(&si->avail_list)); + if (plist_node_empty(&si->avail_list)) + plist_add(&si->avail_list, &swap_avail_head); + spin_unlock(&swap_avail_lock); + } + } + atomic_long_add(nr_entries, &nr_swap_pages); + si->inuse_pages -= nr_entries; + if (si->flags & SWP_BLKDEV) + swap_slot_free_notify = + si->bdev->bd_disk->fops->swap_slot_free_notify; + else + swap_slot_free_notify = NULL; + while (offset <= end) { + frontswap_invalidate_page(si->type, offset); + if (swap_slot_free_notify) + swap_slot_free_notify(si->bdev, offset); + offset++; + } +} + static int scan_swap_map_slots(struct swap_info_struct *si, unsigned char usage, int nr, swp_entry_t slots[]) @@ -676,18 +762,7 @@ static int scan_swap_map_slots(struct swap_info_struct *si, inc_cluster_info_page(si, si->cluster_info, offset); unlock_cluster(ci); - if (offset == si->lowest_bit) - si->lowest_bit++; - if (offset == si->highest_bit) - si->highest_bit--; - si->inuse_pages++; - if (si->inuse_pages == si->pages) { - si->lowest_bit = si->max; - si->highest_bit = 0; - spin_lock(&swap_avail_lock); - plist_del(&si->avail_list, &swap_avail_head); - spin_unlock(&swap_avail_lock); - } + _swap_entry_alloc(si, offset, false); si->cluster_next = offset + 1; slots[n_ret++] = swp_entry(si->type, offset); @@ -766,6 +841,82 @@ static int scan_swap_map_slots(struct swap_info_struct *si, return n_ret; } +#ifdef CONFIG_THP_SWAP_CLUSTER +static void swap_free_huge_cluster(struct swap_info_struct *si, + unsigned long idx) +{ + struct swap_cluster_info *ci; + unsigned long offset = idx * SWAPFILE_CLUSTER; + + ci = lock_cluster(si, offset); + cluster_set_count_flag(ci, 0, 0); + free_cluster(si, idx); + unlock_cluster(ci); + _swap_entry_free(si, offset, true); +} + +static void swapcache_free_trans_huge(struct swap_info_struct *si, + swp_entry_t entry) +{ + unsigned long offset = swp_offset(entry); + unsigned long idx = offset / SWAPFILE_CLUSTER; + struct swap_cluster_info *ci; + unsigned char *map; + unsigned int i; + + spin_lock(&si->lock); + ci = lock_cluster(si, offset); + map = si->swap_map + offset; + for (i = 0; i < SWAPFILE_CLUSTER; i++) { + VM_BUG_ON(map[i] != SWAP_HAS_CACHE); + map[i] = 0; + } + unlock_cluster(ci); + /* Cluster size is same as huge pmd size */ + mem_cgroup_uncharge_swap(entry, HPAGE_PMD_NR); + swap_free_huge_cluster(si, idx); + spin_unlock(&si->lock); +} + +static int swap_alloc_huge_cluster(struct swap_info_struct *si, + swp_entry_t *slot) +{ + unsigned long idx; + struct swap_cluster_info *ci; + unsigned long offset, i; + unsigned char *map; + + if (cluster_list_empty(&si->free_clusters)) + return 0; + + idx = cluster_list_first(&si->free_clusters); + offset = idx * SWAPFILE_CLUSTER; + ci = lock_cluster(si, offset); + alloc_cluster(si, idx); + cluster_set_count_flag(ci, SWAPFILE_CLUSTER, 0); + + map = si->swap_map + offset; + for (i = 0; i < SWAPFILE_CLUSTER; i++) + map[i] = SWAP_HAS_CACHE; + unlock_cluster(ci); + _swap_entry_alloc(si, offset, true); + *slot = swp_entry(si->type, offset); + + return 1; +} +#else +static inline int swap_alloc_huge_cluster(struct swap_info_struct *si, + swp_entry_t *slot) +{ + return 0; +} + +static inline void swapcache_free_trans_huge(struct swap_info_struct *si, + swp_entry_t entry) +{ +} +#endif + static unsigned long scan_swap_map(struct swap_info_struct *si, unsigned char usage) { @@ -781,13 +932,14 @@ static unsigned long scan_swap_map(struct swap_info_struct *si, } -int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) +int get_swap_pages(int n_goal, swp_entry_t swp_entries[], bool huge) { struct swap_info_struct *si, *next; long avail_pgs; int n_ret = 0; + int nr_pages = huge_cluster_nr_entries(huge); - avail_pgs = atomic_long_read(&nr_swap_pages); + avail_pgs = atomic_long_read(&nr_swap_pages) / nr_pages; if (avail_pgs <= 0) goto noswap; @@ -797,7 +949,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) if (n_goal > avail_pgs) n_goal = avail_pgs; - atomic_long_sub(n_goal, &nr_swap_pages); + atomic_long_sub(n_goal * nr_pages, &nr_swap_pages); spin_lock(&swap_avail_lock); @@ -823,10 +975,13 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) spin_unlock(&si->lock); goto nextsi; } - n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, - n_goal, swp_entries); + if (likely(!huge)) + n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, + n_goal, swp_entries); + else + n_ret = swap_alloc_huge_cluster(si, swp_entries); spin_unlock(&si->lock); - if (n_ret) + if (n_ret || unlikely(huge)) goto check_out; pr_debug("scan_swap_map of si %d failed to find offset\n", si->type); @@ -852,7 +1007,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) check_out: if (n_ret < n_goal) - atomic_long_add((long) (n_goal-n_ret), &nr_swap_pages); + atomic_long_add((long)(n_goal-n_ret) * nr_pages, &nr_swap_pages); noswap: return n_ret; } @@ -1008,32 +1163,8 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) dec_cluster_info_page(p, p->cluster_info, offset); unlock_cluster(ci); - mem_cgroup_uncharge_swap(entry); - if (offset < p->lowest_bit) - p->lowest_bit = offset; - if (offset > p->highest_bit) { - bool was_full = !p->highest_bit; - - p->highest_bit = offset; - if (was_full && (p->flags & SWP_WRITEOK)) { - spin_lock(&swap_avail_lock); - WARN_ON(!plist_node_empty(&p->avail_list)); - if (plist_node_empty(&p->avail_list)) - plist_add(&p->avail_list, - &swap_avail_head); - spin_unlock(&swap_avail_lock); - } - } - atomic_long_inc(&nr_swap_pages); - p->inuse_pages--; - frontswap_invalidate_page(p->type, offset); - if (p->flags & SWP_BLKDEV) { - struct gendisk *disk = p->bdev->bd_disk; - - if (disk->fops->swap_slot_free_notify) - disk->fops->swap_slot_free_notify(p->bdev, - offset); - } + mem_cgroup_uncharge_swap(entry, 1); + _swap_entry_free(p, offset, false); } /* @@ -1054,13 +1185,15 @@ void swap_free(swp_entry_t entry) /* * Called after dropping swapcache to decrease refcnt to swap entries. */ -void swapcache_free(swp_entry_t entry) +void swapcache_free(swp_entry_t entry, bool huge) { struct swap_info_struct *p; p = _swap_info_get(entry); if (p) { - if (!__swap_entry_free(p, entry, SWAP_HAS_CACHE)) + if (unlikely(huge)) + swapcache_free_trans_huge(p, entry); + else if (!__swap_entry_free(p, entry, SWAP_HAS_CACHE)) free_swap_slot(entry); } } diff --git a/mm/vmscan.c b/mm/vmscan.c index 58615bb27f2f..6bdf65a38df1 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -708,7 +708,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page); spin_unlock_irqrestore(&mapping->tree_lock, flags); - swapcache_free(swap); + swapcache_free(swap, false); } else { void (*freepage)(struct page *); void *shadow = NULL; -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out 2017-04-06 5:35 ` [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out Huang, Ying @ 2017-04-14 14:58 ` Johannes Weiner 2017-04-15 1:17 ` Huang, Ying 0 siblings, 1 reply; 5+ messages in thread From: Johannes Weiner @ 2017-04-14 14:58 UTC (permalink / raw) To: Huang, Ying Cc: Andrew Morton, linux-mm, linux-kernel, Andrea Arcangeli, Ebru Akagunduz, Michal Hocko, Tejun Heo, Hugh Dickins, Shaohua Li, Minchan Kim, Rik van Riel, cgroups Hi Huang, I reviewed this patch based on the feedback I already provided, but eventually gave up and rewrote it. Please take review feedback more seriously in the future. Attached below is the reworked patch. Most changes are to the layering (page functions, cluster functions, range functions) so that we don't make the lowest swap range code require a notion of huge pages, or make the memcg page functions take size information that can be gathered from the page itself. I turned the config symbol into a generic THP_SWAP that can later be extended when we add 2MB IO. The rest is function naming, #ifdef removal etc. Please review whether this is an acceptable version for you. Thanks --- From b90e48baa752840ba9c52f03a7a792c9b0c5b656 Mon Sep 17 00:00:00 2001 From: Huang Ying <ying.huang@intel.com> Date: Thu, 6 Apr 2017 13:35:13 +0800 Subject: [PATCH] mm, THP, swap: Delay splitting THP during swap out MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In this patch, splitting huge page is delayed from almost the first step of swapping out to after allocating the swap space for the THP (Transparent Huge Page) and adding the THP into the swap cache. This will batch the corresponding operation, thus improve THP swap out throughput. This is the first step for the THP swap optimization. The plan is to delay splitting the THP step by step and avoid splitting the THP finally. The advantages of the THP swap support include: - Batch the swap operations for the THP and reduce lock acquiring/releasing, including allocating/freeing the swap space, adding/deleting to/from the swap cache, and writing/reading the swap space, etc. This will help to improve the THP swap performance. - The THP swap space read/write will be 2M sequential IO. It is particularly helpful for the swap read, which usually are 4k random IO. This will help to improve the THP swap performance. - It will help the memory fragmentation, especially when the THP is heavily used by the applications. The 2M continuous pages will be free up after the THP swapping out. - It will improve the THP utilization on the system with the swap turned on. Because the speed for khugepaged to collapse the normal pages into the THP is quite slow. After the THP is split during the swapping out, it will take quite long time for the normal pages to collapse back into the THP after being swapped in. The high THP utilization helps the efficiency of the page based memory management too. There are some concerns regarding THP swap in, mainly because possible enlarged read/write IO size (for swap in/out) may put more overhead on the storage device. To deal with that, the THP swap in should be turned on only when necessary. For example, it can be selected via "always/never/madvise" logic, to be turned on globally, turned off globally, or turned on only for VMA with MADV_HUGEPAGE, etc. In this patch, one swap cluster is used to hold the contents of each THP swapped out. So, the size of the swap cluster is changed to that of the THP (Transparent Huge Page) on x86_64 architecture (512). For other architectures which want such THP swap optimization, ARCH_USES_THP_SWAP_CLUSTER needs to be selected in the Kconfig file for the architecture. In effect, this will enlarge swap cluster size by 2 times on x86_64. Which may make it harder to find a free cluster when the swap space becomes fragmented. So that, this may reduce the continuous swap space allocation and sequential write in theory. The performance test in 0day shows no regressions caused by this. In the future of THP swap optimization, some information of the swapped out THP (such as compound map count) will be recorded in the swap_cluster_info data structure. The mem cgroup swap accounting functions are enhanced to support charge or uncharge a swap cluster backing a THP as a whole. The swap cluster allocate/free functions are added to allocate/free a swap cluster for a THP. A fair simple algorithm is used for swap cluster allocation, that is, only the first swap device in priority list will be tried to allocate the swap cluster. The function will fail if the trying is not successful, and the caller will fallback to allocate a single swap slot instead. This works good enough for normal cases. If the difference of the number of the free swap clusters among multiple swap devices is significant, it is possible that some THPs are split earlier than necessary. For example, this could be caused by big size difference among multiple swap devices. The swap cache functions is enhanced to support add/delete THP to/from the swap cache as a set of (HPAGE_PMD_NR) sub-pages. This may be enhanced in the future with multi-order radix tree. But because we will split the THP soon during swapping out, that optimization doesn't make much sense for this first step. The THP splitting functions are enhanced to support to split THP in swap cache during swapping out. The page lock will be held during allocating the swap cluster, adding the THP into the swap cache and splitting the THP. So in the code path other than swapping out, if the THP need to be split, the PageSwapCache(THP) will be always false. With the patchset, the swap out throughput improves 14.9% (from about 3.77GB/s to about 4.34GB/s) in the vm-scalability swap-w-seq test case with 8 processes. The test is done on a Xeon E5 v3 system. The swap device used is a RAM simulated PMEM (persistent memory) device. To test the sequential swapping out, the test case creates 8 processes, which sequentially allocate and write to the anonymous pages until the RAM and part of the swap device is used up. The detailed comparison result is as follow, base base+patchset ---------------- -------------------------- %stddev %change %stddev \ | \ 7043990 ± 0% +21.2% 8536807 ± 0% vm-scalability.throughput 109.94 ± 1% -16.2% 92.09 ± 0% vm-scalability.time.elapsed_time 3957091 ± 0% +14.9% 4547173 ± 0% vmstat.swap.so 31.46 ± 1% -38.3% 19.42 ± 0% perf-stat.cache-miss-rate% 1.04 ± 1% +22.2% 1.27 ± 0% perf-stat.ipc 9.33 ± 2% -60.7% 3.67 ± 1% perf-profile.calltrace.cycles-pp.add_to_swap.shrink_page_list.shrink_inactive_list.shrink_node_memcg.shrink_node The swap cluster is only available for SSD, so the THP swap optimization in this patchset has no effect for HDD. [hannes@cmpxchg.org: extensive cleanups and simplifications] Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: cgroups@vger.kernel.org Suggested-by: Andrew Morton <akpm@linux-foundation.org> [for config option] Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> [for changes in huge_memory.c and huge_mm.h] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> --- arch/x86/Kconfig | 1 + include/linux/page-flags.h | 5 +- include/linux/swap.h | 22 +++- include/linux/swap_cgroup.h | 6 +- mm/Kconfig | 12 +++ mm/huge_memory.c | 11 +- mm/memcontrol.c | 49 ++++----- mm/shmem.c | 2 +- mm/swap_cgroup.c | 40 +++++-- mm/swap_slots.c | 17 ++- mm/swap_state.c | 114 ++++++++++++-------- mm/swapfile.c | 246 +++++++++++++++++++++++++++++++------------- 12 files changed, 360 insertions(+), 165 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 9a5af1e1cd61..247e7eed01b7 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -72,6 +72,7 @@ config X86 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP select ARCH_WANT_FRAME_POINTERS select ARCH_WANTS_DYNAMIC_TASK_STRUCT + select ARCH_WANTS_THP_SWAP if X86_64 select BUILDTIME_EXTABLE_SORT select CLKEVT_I8253 select CLOCKSOURCE_VALIDATE_LAST_CYCLE diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 6b5818d6de32..f4acd6c4f808 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -326,11 +326,12 @@ PAGEFLAG_FALSE(HighMem) #ifdef CONFIG_SWAP static __always_inline int PageSwapCache(struct page *page) { + page = compound_head(page); return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); } -SETPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) -CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND) +SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) +CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL) #else PAGEFLAG_FALSE(SwapCache) #endif diff --git a/include/linux/swap.h b/include/linux/swap.h index 486494e6b2fc..34adac6e9457 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -29,6 +29,12 @@ struct bio; SWAP_FLAG_DISCARD_PAGES) #define SWAP_BATCH 64 +#ifdef CONFIG_THP_SWAP +#define SWAPFILE_CLUSTER HPAGE_PMD_NR +#else +#define SWAPFILE_CLUSTER 256 +#endif + static inline int current_is_kswapd(void) { return current->flags & PF_KSWAPD; @@ -386,15 +392,16 @@ static inline long get_nr_swap_pages(void) } extern void si_swapinfo(struct sysinfo *); -extern swp_entry_t get_swap_page(void); +extern swp_entry_t get_swap_page(struct page *); extern swp_entry_t get_swap_page_of_type(int); -extern int get_swap_pages(int n, swp_entry_t swp_entries[]); +extern int get_swap_pages(int n, bool cluster, swp_entry_t swp_entries[]); extern int add_swap_count_continuation(swp_entry_t, gfp_t); extern void swap_shmem_alloc(swp_entry_t); extern int swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern void swap_free(swp_entry_t); extern void swapcache_free(swp_entry_t); +extern void swapcache_free_cluster(swp_entry_t); extern void swapcache_free_entries(swp_entry_t *entries, int n); extern int free_swap_and_cache(swp_entry_t); extern int swap_type_of(dev_t, sector_t, struct block_device **); @@ -460,6 +467,10 @@ static inline void swapcache_free(swp_entry_t swp) { } +static inline void swapcache_free_cluster(swp_entry_t swp) +{ +} + static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, struct vm_area_struct *vma, unsigned long addr) { @@ -518,7 +529,7 @@ static inline int try_to_free_swap(struct page *page) return 0; } -static inline swp_entry_t get_swap_page(void) +static inline swp_entry_t get_swap_page(struct page *page) { swp_entry_t entry; entry.val = 0; @@ -551,7 +562,7 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) #ifdef CONFIG_MEMCG_SWAP extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); -extern void mem_cgroup_uncharge_swap(swp_entry_t entry); +extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages); extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); extern bool mem_cgroup_swap_full(struct page *page); #else @@ -565,7 +576,8 @@ static inline int mem_cgroup_try_charge_swap(struct page *page, return 0; } -static inline void mem_cgroup_uncharge_swap(swp_entry_t entry) +static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, + unsigned int nr_pages) { } diff --git a/include/linux/swap_cgroup.h b/include/linux/swap_cgroup.h index 145306bdc92f..b2b8ec7bda3f 100644 --- a/include/linux/swap_cgroup.h +++ b/include/linux/swap_cgroup.h @@ -7,7 +7,8 @@ extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, unsigned short old, unsigned short new); -extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id); +extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id, + unsigned int nr_ents); extern unsigned short lookup_swap_cgroup_id(swp_entry_t ent); extern int swap_cgroup_swapon(int type, unsigned long max_pages); extern void swap_cgroup_swapoff(int type); @@ -15,7 +16,8 @@ extern void swap_cgroup_swapoff(int type); #else static inline -unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) +unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id, + unsigned int nr_ents) { return 0; } diff --git a/mm/Kconfig b/mm/Kconfig index c89f472b658c..660fb765bf7d 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -447,6 +447,18 @@ choice benefit. endchoice +config ARCH_WANTS_THP_SWAP + def_bool n + +config THP_SWAP + def_bool y + depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP + help + Swap transparent huge pages in one piece, without splitting. + XXX: For now this only does clustered swap space allocation. + + For selection by architectures with reasonable THP sizes. + config TRANSPARENT_HUGE_PAGECACHE def_bool y depends on TRANSPARENT_HUGEPAGE diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d14dd961f626..4a5c1ca21894 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2185,7 +2185,7 @@ static void __split_huge_page_tail(struct page *head, int tail, * atomic_set() here would be safe on all archs (and not only on x86), * it's safer to use atomic_inc()/atomic_add(). */ - if (PageAnon(head)) { + if (PageAnon(head) && !PageSwapCache(head)) { page_ref_inc(page_tail); } else { /* Additional pin to radix tree */ @@ -2196,6 +2196,7 @@ static void __split_huge_page_tail(struct page *head, int tail, page_tail->flags |= (head->flags & ((1L << PG_referenced) | (1L << PG_swapbacked) | + (1L << PG_swapcache) | (1L << PG_mlocked) | (1L << PG_uptodate) | (1L << PG_active) | @@ -2258,7 +2259,11 @@ static void __split_huge_page(struct page *page, struct list_head *list, ClearPageCompound(head); /* See comment in __split_huge_page_tail() */ if (PageAnon(head)) { - page_ref_inc(head); + /* Additional pin to radix tree of swap cache */ + if (PageSwapCache(head)) + page_ref_add(head, 2); + else + page_ref_inc(head); } else { /* Additional pin to radix tree */ page_ref_add(head, 2); @@ -2414,7 +2419,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) ret = -EBUSY; goto out; } - extra_pins = 0; + extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; mapping = NULL; anon_vma_lock_write(anon_vma); } else { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index ff73899af61a..609fd5e1895f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2376,10 +2376,9 @@ void mem_cgroup_split_huge_fixup(struct page *head) #ifdef CONFIG_MEMCG_SWAP static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg, - bool charge) + int nr_entries) { - int val = (charge) ? 1 : -1; - this_cpu_add(memcg->stat->count[MEMCG_SWAP], val); + this_cpu_add(memcg->stat->count[MEMCG_SWAP], nr_entries); } /** @@ -2405,8 +2404,8 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry, new_id = mem_cgroup_id(to); if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { - mem_cgroup_swap_statistics(from, false); - mem_cgroup_swap_statistics(to, true); + mem_cgroup_swap_statistics(from, -1); + mem_cgroup_swap_statistics(to, 1); return 0; } return -EINVAL; @@ -5445,7 +5444,7 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg, * let's not wait for it. The page already received a * memory+swap charge, drop the swap entry duplicate. */ - mem_cgroup_uncharge_swap(entry); + mem_cgroup_uncharge_swap(entry, nr_pages); } } @@ -5873,9 +5872,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) * ancestor for the swap instead and transfer the memory+swap charge. */ swap_memcg = mem_cgroup_id_get_online(memcg); - oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg)); + oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg), 1); VM_BUG_ON_PAGE(oldid, page); - mem_cgroup_swap_statistics(swap_memcg, true); + mem_cgroup_swap_statistics(swap_memcg, 1); page->mem_cgroup = NULL; @@ -5902,19 +5901,20 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) css_put(&memcg->css); } -/* - * mem_cgroup_try_charge_swap - try charging a swap entry +/** + * mem_cgroup_try_charge_swap - try charging swap space for a page * @page: page being added to swap * @entry: swap entry to charge * - * Try to charge @entry to the memcg that @page belongs to. + * Try to charge @page's memcg for the swap space at @entry. * * Returns 0 on success, -ENOMEM on failure. */ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) { - struct mem_cgroup *memcg; + unsigned int nr_pages = hpage_nr_pages(page); struct page_counter *counter; + struct mem_cgroup *memcg; unsigned short oldid; if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account) @@ -5929,25 +5929,26 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) memcg = mem_cgroup_id_get_online(memcg); if (!mem_cgroup_is_root(memcg) && - !page_counter_try_charge(&memcg->swap, 1, &counter)) { + !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) { mem_cgroup_id_put(memcg); return -ENOMEM; } - oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg)); + if (nr_entries > 1) + mem_cgroup_id_get_many(memcg, nr_pages - 1); + oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_pages); VM_BUG_ON_PAGE(oldid, page); - mem_cgroup_swap_statistics(memcg, true); + mem_cgroup_swap_statistics(memcg, nr_pages); return 0; } /** - * mem_cgroup_uncharge_swap - uncharge a swap entry + * mem_cgroup_uncharge_swap - uncharge swap space * @entry: swap entry to uncharge - * - * Drop the swap charge associated with @entry. + * @nr_pages: the amount of swap space to uncharge */ -void mem_cgroup_uncharge_swap(swp_entry_t entry) +void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) { struct mem_cgroup *memcg; unsigned short id; @@ -5955,18 +5956,18 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry) if (!do_swap_account) return; - id = swap_cgroup_record(entry, 0); + id = swap_cgroup_record(entry, 0, nr_pages); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (memcg) { if (!mem_cgroup_is_root(memcg)) { if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) - page_counter_uncharge(&memcg->swap, 1); + page_counter_uncharge(&memcg->swap, nr_pages); else - page_counter_uncharge(&memcg->memsw, 1); + page_counter_uncharge(&memcg->memsw, nr_pages); } - mem_cgroup_swap_statistics(memcg, false); - mem_cgroup_id_put(memcg); + mem_cgroup_swap_statistics(memcg, -nr_pages); + mem_cgroup_id_put_many(memcg, nr_pages); } rcu_read_unlock(); } diff --git a/mm/shmem.c b/mm/shmem.c index e67d6ba4e98e..29948d7da172 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1290,7 +1290,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) SetPageUptodate(page); } - swap = get_swap_page(); + swap = get_swap_page(page); if (!swap.val) goto redirty; diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c index 310ac0b8f974..8cee2d125815 100644 --- a/mm/swap_cgroup.c +++ b/mm/swap_cgroup.c @@ -58,21 +58,27 @@ static int swap_cgroup_prepare(int type) return -ENOMEM; } +static struct swap_cgroup *__lookup_swap_cgroup(struct swap_cgroup_ctrl *ctrl, + pgoff_t offset) +{ + struct page *mappage; + struct swap_cgroup *sc; + + mappage = ctrl->map[offset / SC_PER_PAGE]; + sc = page_address(mappage); + return sc + offset % SC_PER_PAGE; +} + static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent, struct swap_cgroup_ctrl **ctrlp) { pgoff_t offset = swp_offset(ent); struct swap_cgroup_ctrl *ctrl; - struct page *mappage; - struct swap_cgroup *sc; ctrl = &swap_cgroup_ctrl[swp_type(ent)]; if (ctrlp) *ctrlp = ctrl; - - mappage = ctrl->map[offset / SC_PER_PAGE]; - sc = page_address(mappage); - return sc + offset % SC_PER_PAGE; + return __lookup_swap_cgroup(ctrl, offset); } /** @@ -105,25 +111,39 @@ unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, } /** - * swap_cgroup_record - record mem_cgroup for this swp_entry. - * @ent: swap entry to be recorded into + * swap_cgroup_record - record mem_cgroup for a set of swap entries + * @ent: the first swap entry to be recorded into * @id: mem_cgroup to be recorded + * @nr_ents: number of swap entries to be recorded * * Returns old value at success, 0 at failure. * (Of course, old value can be 0.) */ -unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) +unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id, + unsigned int nr_ents) { struct swap_cgroup_ctrl *ctrl; struct swap_cgroup *sc; unsigned short old; unsigned long flags; + pgoff_t offset = swp_offset(ent); + pgoff_t end = offset + nr_ents; sc = lookup_swap_cgroup(ent, &ctrl); spin_lock_irqsave(&ctrl->lock, flags); old = sc->id; - sc->id = id; + for (;;) { + VM_BUG_ON(sc->id != old); + sc->id = id; + offset++; + if (offset == end) + break; + if (offset % SC_PER_PAGE) + sc++; + else + sc = __lookup_swap_cgroup(ctrl, offset); + } spin_unlock_irqrestore(&ctrl->lock, flags); return old; diff --git a/mm/swap_slots.c b/mm/swap_slots.c index aa1c415f4abd..e22e64712b1a 100644 --- a/mm/swap_slots.c +++ b/mm/swap_slots.c @@ -31,6 +31,7 @@ #include <linux/cpumask.h> #include <linux/vmalloc.h> #include <linux/mutex.h> +#include <linux/mm.h> #ifdef CONFIG_SWAP @@ -260,7 +261,8 @@ static int refill_swap_slots_cache(struct swap_slots_cache *cache) cache->cur = 0; if (swap_slot_cache_active) - cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, cache->slots); + cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, false, + cache->slots); return cache->nr; } @@ -298,11 +300,19 @@ int free_swap_slot(swp_entry_t entry) return 0; } -swp_entry_t get_swap_page(void) +swp_entry_t get_swap_page(struct page *page) { swp_entry_t entry, *pentry; struct swap_slots_cache *cache; + entry.val = 0; + + if (PageTransHuge(page)) { + if (hpage_nr_pages(page) == SWAPFILE_CLUSTER) + get_swap_pages(1, true, &entry); + return entry; + } + /* * Preemption is allowed here, because we may sleep * in refill_swap_slots_cache(). But it is safe, because @@ -314,7 +324,6 @@ swp_entry_t get_swap_page(void) */ cache = raw_cpu_ptr(&swp_slots); - entry.val = 0; if (check_cache_active()) { mutex_lock(&cache->alloc_lock); if (cache->slots) { @@ -334,7 +343,7 @@ swp_entry_t get_swap_page(void) return entry; } - get_swap_pages(1, &entry); + get_swap_pages(1, false, &entry); return entry; } diff --git a/mm/swap_state.c b/mm/swap_state.c index 7bfb9bd1ca21..747d0ed2e811 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -19,6 +19,7 @@ #include <linux/migrate.h> #include <linux/vmalloc.h> #include <linux/swap_slots.h> +#include <linux/huge_mm.h> #include <asm/pgtable.h> @@ -38,6 +39,7 @@ struct address_space *swapper_spaces[MAX_SWAPFILES]; static unsigned int nr_swapper_spaces[MAX_SWAPFILES]; #define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0) +#define ADD_CACHE_INFO(x, nr) do { swap_cache_info.x += (nr); } while (0) static struct { unsigned long add_total; @@ -90,39 +92,46 @@ void show_swap_cache_info(void) */ int __add_to_swap_cache(struct page *page, swp_entry_t entry) { - int error; + int error, i, nr = hpage_nr_pages(page); struct address_space *address_space; + pgoff_t idx = swp_offset(entry); VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(PageSwapCache(page), page); VM_BUG_ON_PAGE(!PageSwapBacked(page), page); - get_page(page); + page_ref_add(page, nr); SetPageSwapCache(page); - set_page_private(page, entry.val); address_space = swap_address_space(entry); spin_lock_irq(&address_space->tree_lock); - error = radix_tree_insert(&address_space->page_tree, - swp_offset(entry), page); - if (likely(!error)) { - address_space->nrpages++; - __inc_node_page_state(page, NR_FILE_PAGES); - INC_CACHE_INFO(add_total); + for (i = 0; i < nr; i++) { + set_page_private(page + i, entry.val + i); + error = radix_tree_insert(&address_space->page_tree, + idx + i, page + i); + if (unlikely(error)) + break; } - spin_unlock_irq(&address_space->tree_lock); - - if (unlikely(error)) { + if (likely(!error)) { + address_space->nrpages += nr; + __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr); + ADD_CACHE_INFO(add_total, nr); + } else { /* * Only the context which have set SWAP_HAS_CACHE flag * would call add_to_swap_cache(). * So add_to_swap_cache() doesn't returns -EEXIST. */ VM_BUG_ON(error == -EEXIST); - set_page_private(page, 0UL); + set_page_private(page + i, 0UL); + while (i--) { + radix_tree_delete(&address_space->page_tree, idx + i); + set_page_private(page + i, 0UL); + } ClearPageSwapCache(page); - put_page(page); + page_ref_sub(page, nr); } + spin_unlock_irq(&address_space->tree_lock); return error; } @@ -132,7 +141,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) { int error; - error = radix_tree_maybe_preload(gfp_mask); + error = radix_tree_maybe_preload_order(gfp_mask, compound_order(page)); if (!error) { error = __add_to_swap_cache(page, entry); radix_tree_preload_end(); @@ -146,8 +155,10 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask) */ void __delete_from_swap_cache(struct page *page) { - swp_entry_t entry; struct address_space *address_space; + int i, nr = hpage_nr_pages(page); + swp_entry_t entry; + pgoff_t idx; VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageSwapCache(page), page); @@ -155,12 +166,15 @@ void __delete_from_swap_cache(struct page *page) entry.val = page_private(page); address_space = swap_address_space(entry); - radix_tree_delete(&address_space->page_tree, swp_offset(entry)); - set_page_private(page, 0); + idx = swp_offset(entry); + for (i = 0; i < nr; i++) { + radix_tree_delete(&address_space->page_tree, idx + i); + set_page_private(page + i, 0); + } ClearPageSwapCache(page); - address_space->nrpages--; - __dec_node_page_state(page, NR_FILE_PAGES); - INC_CACHE_INFO(del_total); + address_space->nrpages -= nr; + __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr); + ADD_CACHE_INFO(del_total, nr); } /** @@ -178,20 +192,12 @@ int add_to_swap(struct page *page, struct list_head *list) VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageUptodate(page), page); - entry = get_swap_page(); +retry: + entry = get_swap_page(page); if (!entry.val) - return 0; - - if (mem_cgroup_try_charge_swap(page, entry)) { - swapcache_free(entry); - return 0; - } - - if (unlikely(PageTransHuge(page))) - if (unlikely(split_huge_page_to_list(page, list))) { - swapcache_free(entry); - return 0; - } + goto fail; + if (mem_cgroup_try_charge_swap(page, entry)) + goto fail_free; /* * Radix-tree node allocations from PF_MEMALLOC contexts could @@ -206,17 +212,33 @@ int add_to_swap(struct page *page, struct list_head *list) */ err = add_to_swap_cache(page, entry, __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN); - - if (!err) { - return 1; - } else { /* -ENOMEM radix-tree allocation failure */ + /* -ENOMEM radix-tree allocation failure */ + if (err) /* * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry); - return 0; + goto fail_free; + + if (unlikely(PageTransHuge(page))) { + err = split_huge_page_to_list(page, list); + if (err) { + delete_from_swap_cache(page); + return 0; + } } + + return 1; + +fail_free: + if (PageTransHuge(page)) + swapcache_free_cluster(entry); + else + swapcache_free(entry); +fail: + if (PageTransHuge(page) && !split_huge_page_to_list(page, list)) + goto retry; + return 0; } /* @@ -237,8 +259,12 @@ void delete_from_swap_cache(struct page *page) __delete_from_swap_cache(page); spin_unlock_irq(&address_space->tree_lock); - swapcache_free(entry); - put_page(page); + if (PageTransHuge(page)) + swapcache_free_cluster(entry); + else + swapcache_free(entry); + + page_ref_sub(page, hpage_nr_pages(page)); } /* @@ -295,7 +321,7 @@ struct page * lookup_swap_cache(swp_entry_t entry) page = find_get_page(swap_address_space(entry), swp_offset(entry)); - if (page) { + if (page && likely(!PageTransCompound(page))) { INC_CACHE_INFO(find_success); if (TestClearPageReadahead(page)) atomic_inc(&swapin_readahead_hits); @@ -506,7 +532,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, gfp_mask, vma, addr); if (!page) continue; - if (offset != entry_offset) + if (offset != entry_offset && likely(!PageTransCompound(page))) SetPageReadahead(page); put_page(page); } diff --git a/mm/swapfile.c b/mm/swapfile.c index 53b5881ee0d6..f597cabcaab7 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -199,7 +199,6 @@ static void discard_swap_cluster(struct swap_info_struct *si, } } -#define SWAPFILE_CLUSTER 256 #define LATENCY_LIMIT 256 static inline void cluster_set_flag(struct swap_cluster_info *info, @@ -374,6 +373,14 @@ static void swap_cluster_schedule_discard(struct swap_info_struct *si, schedule_work(&si->discard_work); } +static void __free_cluster(struct swap_info_struct *si, unsigned long idx) +{ + struct swap_cluster_info *ci = si->cluster_info; + + cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); + cluster_list_add_tail(&si->free_clusters, ci, idx); +} + /* * Doing discard actually. After a cluster discard is finished, the cluster * will be added to free cluster list. caller should hold si->lock. @@ -394,10 +401,7 @@ static void swap_do_scheduled_discard(struct swap_info_struct *si) spin_lock(&si->lock); ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); - cluster_set_flag(ci, CLUSTER_FLAG_FREE); - unlock_cluster(ci); - cluster_list_add_tail(&si->free_clusters, info, idx); - ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); + __free_cluster(si, idx); memset(si->swap_map + idx * SWAPFILE_CLUSTER, 0, SWAPFILE_CLUSTER); unlock_cluster(ci); @@ -415,6 +419,34 @@ static void swap_discard_work(struct work_struct *work) spin_unlock(&si->lock); } +static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) +{ + struct swap_cluster_info *ci = si->cluster_info; + + VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); + cluster_list_del_first(&si->free_clusters, ci); + cluster_set_count_flag(ci + idx, 0, 0); +} + +static void free_cluster(struct swap_info_struct *si, unsigned long idx) +{ + struct swap_cluster_info *ci = si->cluster_info + idx; + + VM_BUG_ON(cluster_count(ci) != 0); + /* + * If the swap is discardable, prepare discard the cluster + * instead of free it immediately. The cluster will be freed + * after discard. + */ + if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == + (SWP_WRITEOK | SWP_PAGE_DISCARD)) { + swap_cluster_schedule_discard(si, idx); + return; + } + + __free_cluster(si, idx); +} + /* * The cluster corresponding to page_nr will be used. The cluster will be * removed from free cluster list and its usage counter will be increased. @@ -426,11 +458,8 @@ static void inc_cluster_info_page(struct swap_info_struct *p, if (!cluster_info) return; - if (cluster_is_free(&cluster_info[idx])) { - VM_BUG_ON(cluster_list_first(&p->free_clusters) != idx); - cluster_list_del_first(&p->free_clusters, cluster_info); - cluster_set_count_flag(&cluster_info[idx], 0, 0); - } + if (cluster_is_free(&cluster_info[idx])) + alloc_cluster(p, idx); VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); cluster_set_count(&cluster_info[idx], @@ -454,21 +483,8 @@ static void dec_cluster_info_page(struct swap_info_struct *p, cluster_set_count(&cluster_info[idx], cluster_count(&cluster_info[idx]) - 1); - if (cluster_count(&cluster_info[idx]) == 0) { - /* - * If the swap is discardable, prepare discard the cluster - * instead of free it immediately. The cluster will be freed - * after discard. - */ - if ((p->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == - (SWP_WRITEOK | SWP_PAGE_DISCARD)) { - swap_cluster_schedule_discard(p, idx); - return; - } - - cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); - cluster_list_add_tail(&p->free_clusters, cluster_info, idx); - } + if (cluster_count(&cluster_info[idx]) == 0) + free_cluster(p, idx); } /* @@ -558,6 +574,60 @@ static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, return found_free; } +static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, + unsigned int nr_entries) +{ + unsigned int end = offset + nr_entries - 1; + + if (offset == si->lowest_bit) + si->lowest_bit += nr_entries; + if (end == si->highest_bit) + si->highest_bit -= nr_entries; + si->inuse_pages += nr_entries; + if (si->inuse_pages == si->pages) { + si->lowest_bit = si->max; + si->highest_bit = 0; + spin_lock(&swap_avail_lock); + plist_del(&si->avail_list, &swap_avail_head); + spin_unlock(&swap_avail_lock); + } +} + +static void swap_range_free(struct swap_info_struct *si, unsigned long offset, + unsigned int nr_entries) +{ + unsigned long end = offset + nr_entries - 1; + void (*swap_slot_free_notify)(struct block_device *, unsigned long); + + if (offset < si->lowest_bit) + si->lowest_bit = offset; + if (end > si->highest_bit) { + bool was_full = !si->highest_bit; + + si->highest_bit = end; + if (was_full && (si->flags & SWP_WRITEOK)) { + spin_lock(&swap_avail_lock); + WARN_ON(!plist_node_empty(&si->avail_list)); + if (plist_node_empty(&si->avail_list)) + plist_add(&si->avail_list, &swap_avail_head); + spin_unlock(&swap_avail_lock); + } + } + atomic_long_add(nr_entries, &nr_swap_pages); + si->inuse_pages -= nr_entries; + if (si->flags & SWP_BLKDEV) + swap_slot_free_notify = + si->bdev->bd_disk->fops->swap_slot_free_notify; + else + swap_slot_free_notify = NULL; + while (offset <= end) { + frontswap_invalidate_page(si->type, offset); + if (swap_slot_free_notify) + swap_slot_free_notify(si->bdev, offset); + offset++; + } +} + static int scan_swap_map_slots(struct swap_info_struct *si, unsigned char usage, int nr, swp_entry_t slots[]) @@ -676,18 +746,7 @@ static int scan_swap_map_slots(struct swap_info_struct *si, inc_cluster_info_page(si, si->cluster_info, offset); unlock_cluster(ci); - if (offset == si->lowest_bit) - si->lowest_bit++; - if (offset == si->highest_bit) - si->highest_bit--; - si->inuse_pages++; - if (si->inuse_pages == si->pages) { - si->lowest_bit = si->max; - si->highest_bit = 0; - spin_lock(&swap_avail_lock); - plist_del(&si->avail_list, &swap_avail_head); - spin_unlock(&swap_avail_lock); - } + swap_range_alloc(si, offset, 1); si->cluster_next = offset + 1; slots[n_ret++] = swp_entry(si->type, offset); @@ -766,6 +825,44 @@ static int scan_swap_map_slots(struct swap_info_struct *si, return n_ret; } +static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) +{ + unsigned long idx; + struct swap_cluster_info *ci; + unsigned long offset, i; + unsigned char *map; + + if (cluster_list_empty(&si->free_clusters)) + return 0; + + idx = cluster_list_first(&si->free_clusters); + offset = idx * SWAPFILE_CLUSTER; + ci = lock_cluster(si, offset); + alloc_cluster(si, idx); + cluster_set_count_flag(ci, SWAPFILE_CLUSTER, 0); + + map = si->swap_map + offset; + for (i = 0; i < SWAPFILE_CLUSTER; i++) + map[i] = SWAP_HAS_CACHE; + unlock_cluster(ci); + swap_range_alloc(si, offset, SWAPFILE_CLUSTER); + *slot = swp_entry(si->type, offset); + + return 1; +} + +static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) +{ + unsigned long offset = idx * SWAPFILE_CLUSTER; + struct swap_cluster_info *ci; + + ci = lock_cluster(si, offset); + cluster_set_count_flag(ci, 0, 0); + free_cluster(si, idx); + unlock_cluster(ci); + swap_range_free(si, offset, SWAPFILE_CLUSTER); +} + static unsigned long scan_swap_map(struct swap_info_struct *si, unsigned char usage) { @@ -781,13 +878,17 @@ static unsigned long scan_swap_map(struct swap_info_struct *si, } -int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) +int get_swap_pages(int n_goal, bool cluster, swp_entry_t swp_entries[]) { + unsigned long nr_pages = cluster ? SWAPFILE_CLUSTER : 1; struct swap_info_struct *si, *next; long avail_pgs; int n_ret = 0; - avail_pgs = atomic_long_read(&nr_swap_pages); + /* Only single cluster request supported */ + WARN_ON_ONCE(n_goal > 1 && cluster); + + avail_pgs = atomic_long_read(&nr_swap_pages) / nr_pages; if (avail_pgs <= 0) goto noswap; @@ -797,7 +898,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) if (n_goal > avail_pgs) n_goal = avail_pgs; - atomic_long_sub(n_goal, &nr_swap_pages); + atomic_long_sub(n_goal * nr_pages, &nr_swap_pages); spin_lock(&swap_avail_lock); @@ -823,10 +924,13 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) spin_unlock(&si->lock); goto nextsi; } - n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, - n_goal, swp_entries); + if (likely(cluster)) + n_ret = swap_alloc_cluster(si, swp_entries); + else + n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, + n_goal, swp_entries); spin_unlock(&si->lock); - if (n_ret) + if (n_ret || unlikely(cluster)) goto check_out; pr_debug("scan_swap_map of si %d failed to find offset\n", si->type); @@ -852,7 +956,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[]) check_out: if (n_ret < n_goal) - atomic_long_add((long) (n_goal-n_ret), &nr_swap_pages); + atomic_long_add((long)(n_goal-n_ret) * nr_pages, &nr_swap_pages); noswap: return n_ret; } @@ -1008,32 +1112,8 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) dec_cluster_info_page(p, p->cluster_info, offset); unlock_cluster(ci); - mem_cgroup_uncharge_swap(entry); - if (offset < p->lowest_bit) - p->lowest_bit = offset; - if (offset > p->highest_bit) { - bool was_full = !p->highest_bit; - - p->highest_bit = offset; - if (was_full && (p->flags & SWP_WRITEOK)) { - spin_lock(&swap_avail_lock); - WARN_ON(!plist_node_empty(&p->avail_list)); - if (plist_node_empty(&p->avail_list)) - plist_add(&p->avail_list, - &swap_avail_head); - spin_unlock(&swap_avail_lock); - } - } - atomic_long_inc(&nr_swap_pages); - p->inuse_pages--; - frontswap_invalidate_page(p->type, offset); - if (p->flags & SWP_BLKDEV) { - struct gendisk *disk = p->bdev->bd_disk; - - if (disk->fops->swap_slot_free_notify) - disk->fops->swap_slot_free_notify(p->bdev, - offset); - } + mem_cgroup_uncharge_swap(entry, 1); + swap_range_free(p, offset, 1); } /* @@ -1065,6 +1145,32 @@ void swapcache_free(swp_entry_t entry) } } +void swapcache_free_cluster(swp_entry_t entry) +{ + unsigned long offset = swp_offset(entry); + unsigned long idx = offset / SWAPFILE_CLUSTER; + struct swap_cluster_info *ci; + struct swap_info_struct *si; + unsigned char *map; + unsigned int i; + + si = _swap_info_get(entry); + if (!si) + return; + + spin_lock(&si->lock); + ci = lock_cluster(si, offset); + map = si->swap_map + offset; + for (i = 0; i < SWAPFILE_CLUSTER; i++) { + VM_BUG_ON(map[i] != SWAP_HAS_CACHE); + map[i] = 0; + } + unlock_cluster(ci); + mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); + swap_free_cluster(si, idx); + spin_unlock(&si->lock); +} + void swapcache_free_entries(swp_entry_t *entries, int n) { struct swap_info_struct *p, *prev; -- 2.12.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out 2017-04-14 14:58 ` Johannes Weiner @ 2017-04-15 1:17 ` Huang, Ying 2017-04-17 18:24 ` Johannes Weiner 0 siblings, 1 reply; 5+ messages in thread From: Huang, Ying @ 2017-04-15 1:17 UTC (permalink / raw) To: Johannes Weiner Cc: Huang, Ying, Andrew Morton, linux-mm, linux-kernel, Andrea Arcangeli, Ebru Akagunduz, Michal Hocko, Tejun Heo, Hugh Dickins, Shaohua Li, Minchan Kim, Rik van Riel, cgroups Hi, Johannes, Johannes Weiner <hannes@cmpxchg.org> writes: > Hi Huang, > > I reviewed this patch based on the feedback I already provided, but > eventually gave up and rewrote it. Please take review feedback more > seriously in the future. Thanks a lot for your help! I do respect all your review and effort. The -v8 patch doesn't take all your comments, just because I thought we have not reach consensus for some points and I want to use -v8 patch to discuss them. One concern I have before is whether to split THP firstly when swap space or memcg swap is used up. Now I think your solution is acceptable. And if we receive any regression report for that in the future, it's not very hard to deal with. > Attached below is the reworked patch. Most changes are to the layering > (page functions, cluster functions, range functions) so that we don't > make the lowest swap range code require a notion of huge pages, or > make the memcg page functions take size information that can be > gathered from the page itself. I turned the config symbol into a > generic THP_SWAP that can later be extended when we add 2MB IO. The > rest is function naming, #ifdef removal etc. For some #ifdef in swapfile.c, it is to avoid unnecessary code size increase for !CONFIG_TRANSPARENT_HUGEPAGE or platform with THP swap optimization disabled. Is it an issue? > Please review whether this is an acceptable version for you. Yes. It is good for me. I will give it more test on next Monday. [...] > diff --git a/mm/Kconfig b/mm/Kconfig > index c89f472b658c..660fb765bf7d 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -447,6 +447,18 @@ choice > benefit. > endchoice > > +config ARCH_WANTS_THP_SWAP > + def_bool n > + > +config THP_SWAP > + def_bool y > + depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP > + help > + Swap transparent huge pages in one piece, without splitting. > + XXX: For now this only does clustered swap space allocation. Is 'XXX' here intended. > + > + For selection by architectures with reasonable THP sizes. > + > config TRANSPARENT_HUGE_PAGECACHE > def_bool y > depends on TRANSPARENT_HUGEPAGE > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index d14dd961f626..4a5c1ca21894 100644 [...] Best Regards, Huang, Ying -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out 2017-04-15 1:17 ` Huang, Ying @ 2017-04-17 18:24 ` Johannes Weiner [not found] ` <20170417182410.GA26500-druUgvl0LCNAfugRpC6u6w@public.gmane.org> 0 siblings, 1 reply; 5+ messages in thread From: Johannes Weiner @ 2017-04-17 18:24 UTC (permalink / raw) To: Huang, Ying Cc: Andrew Morton, linux-mm, linux-kernel, Andrea Arcangeli, Ebru Akagunduz, Michal Hocko, Tejun Heo, Hugh Dickins, Shaohua Li, Minchan Kim, Rik van Riel, cgroups On Sat, Apr 15, 2017 at 09:17:04AM +0800, Huang, Ying wrote: > Hi, Johannes, > > Johannes Weiner <hannes@cmpxchg.org> writes: > > > Hi Huang, > > > > I reviewed this patch based on the feedback I already provided, but > > eventually gave up and rewrote it. Please take review feedback more > > seriously in the future. > > Thanks a lot for your help! I do respect all your review and effort. > The -v8 patch doesn't take all your comments, just because I thought we > have not reach consensus for some points and I want to use -v8 patch to > discuss them. > > One concern I have before is whether to split THP firstly when swap > space or memcg swap is used up. Now I think your solution is > acceptable. And if we receive any regression report for that in the > future, it's not very hard to deal with. If you look at get_scan_count(), we'll stop scanning anonymous pages altogether when swap space runs out. So it might happen to a few THP, but it shouldn't be a big deal. And yes, in that case I'd really rather wait for any real problems to materialize before we complicate things. > > Attached below is the reworked patch. Most changes are to the layering > > (page functions, cluster functions, range functions) so that we don't > > make the lowest swap range code require a notion of huge pages, or > > make the memcg page functions take size information that can be > > gathered from the page itself. I turned the config symbol into a > > generic THP_SWAP that can later be extended when we add 2MB IO. The > > rest is function naming, #ifdef removal etc. > > For some #ifdef in swapfile.c, it is to avoid unnecessary code size > increase for !CONFIG_TRANSPARENT_HUGEPAGE or platform with THP swap > optimization disabled. Is it an issue? It saves some code size, but it looks like the biggest cost comes from bloating PageSwapCache(). This is mm/builtin.o with !CONFIG_THP: add/remove: 1/0 grow/shrink: 34/5 up/down: 920/-311 (609) function old new delta __free_cluster - 106 +106 get_swap_pages 465 555 +90 migrate_page_move_mapping 1404 1479 +75 shrink_page_list 3573 3632 +59 __delete_from_swap_cache 235 293 +58 __test_set_page_writeback 626 678 +52 __swap_writepage 766 812 +46 try_to_unuse 1763 1795 +32 madvise_free_pte_range 882 912 +30 __set_page_dirty_nobuffers 245 268 +23 migrate_page_copy 565 587 +22 swap_slot_free_notify 133 151 +18 shmem_replace_page 616 633 +17 try_to_free_swap 135 151 +16 test_clear_page_writeback 512 528 +16 swap_set_page_dirty 109 125 +16 swap_readpage 384 400 +16 shmem_unuse 1535 1551 +16 reuse_swap_page 340 356 +16 page_mapping 144 160 +16 migrate_huge_page_move_mapping 483 499 +16 free_swap_and_cache 409 425 +16 free_pages_and_swap_cache 161 177 +16 free_page_and_swap_cache 145 161 +16 do_swap_page 1216 1232 +16 __remove_mapping 408 424 +16 __page_file_mapping 82 98 +16 __page_file_index 70 85 +15 try_to_unmap_one 1324 1337 +13 shmem_getpage_gfp.isra 2358 2371 +13 add_to_swap_cache 47 60 +13 inc_cluster_info_page 204 210 +6 get_swap_page 411 415 +4 shmem_writepage 922 925 +3 sys_swapon 4210 4211 +1 swapcache_free_entries 786 768 -18 __add_to_swap_cache 445 406 -39 delete_from_swap_cache 149 104 -45 scan_swap_map_slots 1953 1889 -64 swap_do_scheduled_discard 713 568 -145 Total: Before=454535, After=455144, chg +0.13% If I make the compound_head() in there conditional, this patch actually ends up shrinking the code due to the refactoring of the cluster functions: add/remove: 1/0 grow/shrink: 10/5 up/down: 302/-327 (-25) function old new delta __free_cluster - 106 +106 get_swap_pages 465 555 +90 __delete_from_swap_cache 235 277 +42 shmem_replace_page 616 633 +17 migrate_page_move_mapping 1404 1418 +14 add_to_swap_cache 47 60 +13 migrate_page_copy 565 571 +6 inc_cluster_info_page 204 210 +6 get_swap_page 411 415 +4 shmem_writepage 922 925 +3 sys_swapon 4210 4211 +1 swapcache_free_entries 786 768 -18 delete_from_swap_cache 149 104 -45 __add_to_swap_cache 445 390 -55 scan_swap_map_slots 1953 1889 -64 swap_do_scheduled_discard 713 568 -145 Total: Before=454535, After=454510, chg -0.01% But PageSwapCache() is somewhat ugly either way. Even with THP_SWAP compiled in, it seems like most callsites wouldn't test tailpages? Can we get rid of the compound_head() and annotate any callsites working on potential tail pages? > > Please review whether this is an acceptable version for you. > > Yes. It is good for me. I will give it more test on next Monday. Thanks diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index f4acd6c4f808..d33e3280c8ad 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -326,7 +326,9 @@ PAGEFLAG_FALSE(HighMem) #ifdef CONFIG_SWAP static __always_inline int PageSwapCache(struct page *page) { +#ifdef CONFIG_THP_SWAP page = compound_head(page); +#endif return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); } diff --git a/include/linux/swap.h b/include/linux/swap.h index 34adac6e9457..a4dba6975e7b 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -401,7 +401,6 @@ extern int swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern void swap_free(swp_entry_t); extern void swapcache_free(swp_entry_t); -extern void swapcache_free_cluster(swp_entry_t); extern void swapcache_free_entries(swp_entry_t *entries, int n); extern int free_swap_and_cache(swp_entry_t); extern int swap_type_of(dev_t, sector_t, struct block_device **); @@ -467,10 +466,6 @@ static inline void swapcache_free(swp_entry_t swp) { } -static inline void swapcache_free_cluster(swp_entry_t swp) -{ -} - static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, struct vm_area_struct *vma, unsigned long addr) { @@ -592,5 +587,13 @@ static inline bool mem_cgroup_swap_full(struct page *page) } #endif +#ifdef CONFIG_THP_SWAP +extern void swapcache_free_cluster(swp_entry_t); +#else +static inline void swapcache_free_cluster(swp_entry_t swp) +{ +} +#endif + #endif /* __KERNEL__*/ #endif /* _LINUX_SWAP_H */ diff --git a/mm/swapfile.c b/mm/swapfile.c index f597cabcaab7..eeaf145b2a20 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -825,6 +825,7 @@ static int scan_swap_map_slots(struct swap_info_struct *si, return n_ret; } +#ifdef CONFIG_THP_SWAP static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) { unsigned long idx; @@ -862,6 +863,13 @@ static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) unlock_cluster(ci); swap_range_free(si, offset, SWAPFILE_CLUSTER); } +#else +static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) +{ + VM_WARN_ON_ONCE(1); + return 0; +} +#endif /* CONFIG_THP_SWAP */ static unsigned long scan_swap_map(struct swap_info_struct *si, unsigned char usage) @@ -1145,6 +1153,7 @@ void swapcache_free(swp_entry_t entry) } } +#ifdef CONFIG_THP_SWAP void swapcache_free_cluster(swp_entry_t entry) { unsigned long offset = swp_offset(entry); @@ -1170,6 +1179,7 @@ void swapcache_free_cluster(swp_entry_t entry) swap_free_cluster(si, idx); spin_unlock(&si->lock); } +#endif /* CONFIG_THP_SWAP */ void swapcache_free_entries(swp_entry_t *entries, int n) { -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 5+ messages in thread
[parent not found: <20170417182410.GA26500-druUgvl0LCNAfugRpC6u6w@public.gmane.org>]
* Re: [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out [not found] ` <20170417182410.GA26500-druUgvl0LCNAfugRpC6u6w@public.gmane.org> @ 2017-04-18 0:33 ` Huang, Ying 0 siblings, 0 replies; 5+ messages in thread From: Huang, Ying @ 2017-04-18 0:33 UTC (permalink / raw) To: Johannes Weiner Cc: Huang, Ying, Andrew Morton, linux-mm-Bw31MaZKKs3YtjvyW6yDsg, linux-kernel-u79uwXL29TY76Z2rM5mHXA, Andrea Arcangeli, Ebru Akagunduz, Michal Hocko, Tejun Heo, Hugh Dickins, Shaohua Li, Minchan Kim, Rik van Riel, cgroups-u79uwXL29TY76Z2rM5mHXA Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> writes: > On Sat, Apr 15, 2017 at 09:17:04AM +0800, Huang, Ying wrote: >> Hi, Johannes, >> >> Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> writes: >> >> > Hi Huang, >> > >> > I reviewed this patch based on the feedback I already provided, but >> > eventually gave up and rewrote it. Please take review feedback more >> > seriously in the future. >> >> Thanks a lot for your help! I do respect all your review and effort. >> The -v8 patch doesn't take all your comments, just because I thought we >> have not reach consensus for some points and I want to use -v8 patch to >> discuss them. >> >> One concern I have before is whether to split THP firstly when swap >> space or memcg swap is used up. Now I think your solution is >> acceptable. And if we receive any regression report for that in the >> future, it's not very hard to deal with. > > If you look at get_scan_count(), we'll stop scanning anonymous pages > altogether when swap space runs out. So it might happen to a few THP, > but it shouldn't be a big deal. Yes. It only influences a few THP. > And yes, in that case I'd really rather wait for any real problems to > materialize before we complicate things. > >> > Attached below is the reworked patch. Most changes are to the layering >> > (page functions, cluster functions, range functions) so that we don't >> > make the lowest swap range code require a notion of huge pages, or >> > make the memcg page functions take size information that can be >> > gathered from the page itself. I turned the config symbol into a >> > generic THP_SWAP that can later be extended when we add 2MB IO. The >> > rest is function naming, #ifdef removal etc. >> >> For some #ifdef in swapfile.c, it is to avoid unnecessary code size >> increase for !CONFIG_TRANSPARENT_HUGEPAGE or platform with THP swap >> optimization disabled. Is it an issue? > > It saves some code size, but it looks like the biggest cost comes from > bloating PageSwapCache(). This is mm/builtin.o with !CONFIG_THP: > > add/remove: 1/0 grow/shrink: 34/5 up/down: 920/-311 (609) > function old new delta > __free_cluster - 106 +106 > get_swap_pages 465 555 +90 > migrate_page_move_mapping 1404 1479 +75 > shrink_page_list 3573 3632 +59 > __delete_from_swap_cache 235 293 +58 > __test_set_page_writeback 626 678 +52 > __swap_writepage 766 812 +46 > try_to_unuse 1763 1795 +32 > madvise_free_pte_range 882 912 +30 > __set_page_dirty_nobuffers 245 268 +23 > migrate_page_copy 565 587 +22 > swap_slot_free_notify 133 151 +18 > shmem_replace_page 616 633 +17 > try_to_free_swap 135 151 +16 > test_clear_page_writeback 512 528 +16 > swap_set_page_dirty 109 125 +16 > swap_readpage 384 400 +16 > shmem_unuse 1535 1551 +16 > reuse_swap_page 340 356 +16 > page_mapping 144 160 +16 > migrate_huge_page_move_mapping 483 499 +16 > free_swap_and_cache 409 425 +16 > free_pages_and_swap_cache 161 177 +16 > free_page_and_swap_cache 145 161 +16 > do_swap_page 1216 1232 +16 > __remove_mapping 408 424 +16 > __page_file_mapping 82 98 +16 > __page_file_index 70 85 +15 > try_to_unmap_one 1324 1337 +13 > shmem_getpage_gfp.isra 2358 2371 +13 > add_to_swap_cache 47 60 +13 > inc_cluster_info_page 204 210 +6 > get_swap_page 411 415 +4 > shmem_writepage 922 925 +3 > sys_swapon 4210 4211 +1 > swapcache_free_entries 786 768 -18 > __add_to_swap_cache 445 406 -39 > delete_from_swap_cache 149 104 -45 > scan_swap_map_slots 1953 1889 -64 > swap_do_scheduled_discard 713 568 -145 > Total: Before=454535, After=455144, chg +0.13% > > If I make the compound_head() in there conditional, this patch > actually ends up shrinking the code due to the refactoring of the > cluster functions: > > add/remove: 1/0 grow/shrink: 10/5 up/down: 302/-327 (-25) > function old new delta > __free_cluster - 106 +106 > get_swap_pages 465 555 +90 > __delete_from_swap_cache 235 277 +42 > shmem_replace_page 616 633 +17 > migrate_page_move_mapping 1404 1418 +14 > add_to_swap_cache 47 60 +13 > migrate_page_copy 565 571 +6 > inc_cluster_info_page 204 210 +6 > get_swap_page 411 415 +4 > shmem_writepage 922 925 +3 > sys_swapon 4210 4211 +1 > swapcache_free_entries 786 768 -18 > delete_from_swap_cache 149 104 -45 > __add_to_swap_cache 445 390 -55 > scan_swap_map_slots 1953 1889 -64 > swap_do_scheduled_discard 713 568 -145 > Total: Before=454535, After=454510, chg -0.01% This looks great! Thanks! > But PageSwapCache() is somewhat ugly either way. Even with THP_SWAP > compiled in, it seems like most callsites wouldn't test tailpages? > Can we get rid of the compound_head() and annotate any callsites > working on potential tail pages? I think we can keep the current #ifdef version and make some cleanup in the next step? >> > Please review whether this is an acceptable version for you. >> >> Yes. It is good for me. I will give it more test on next Monday. > > Thanks I think we will fold the below patch into the original one? Best Regards, Huang, Ying > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index f4acd6c4f808..d33e3280c8ad 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -326,7 +326,9 @@ PAGEFLAG_FALSE(HighMem) > #ifdef CONFIG_SWAP > static __always_inline int PageSwapCache(struct page *page) > { > +#ifdef CONFIG_THP_SWAP > page = compound_head(page); > +#endif > return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags); > > } > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 34adac6e9457..a4dba6975e7b 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -401,7 +401,6 @@ extern int swap_duplicate(swp_entry_t); > extern int swapcache_prepare(swp_entry_t); > extern void swap_free(swp_entry_t); > extern void swapcache_free(swp_entry_t); > -extern void swapcache_free_cluster(swp_entry_t); > extern void swapcache_free_entries(swp_entry_t *entries, int n); > extern int free_swap_and_cache(swp_entry_t); > extern int swap_type_of(dev_t, sector_t, struct block_device **); > @@ -467,10 +466,6 @@ static inline void swapcache_free(swp_entry_t swp) > { > } > > -static inline void swapcache_free_cluster(swp_entry_t swp) > -{ > -} > - > static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask, > struct vm_area_struct *vma, unsigned long addr) > { > @@ -592,5 +587,13 @@ static inline bool mem_cgroup_swap_full(struct page *page) > } > #endif > > +#ifdef CONFIG_THP_SWAP > +extern void swapcache_free_cluster(swp_entry_t); > +#else > +static inline void swapcache_free_cluster(swp_entry_t swp) > +{ > +} > +#endif > + > #endif /* __KERNEL__*/ > #endif /* _LINUX_SWAP_H */ > diff --git a/mm/swapfile.c b/mm/swapfile.c > index f597cabcaab7..eeaf145b2a20 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -825,6 +825,7 @@ static int scan_swap_map_slots(struct swap_info_struct *si, > return n_ret; > } > > +#ifdef CONFIG_THP_SWAP > static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) > { > unsigned long idx; > @@ -862,6 +863,13 @@ static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) > unlock_cluster(ci); > swap_range_free(si, offset, SWAPFILE_CLUSTER); > } > +#else > +static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) > +{ > + VM_WARN_ON_ONCE(1); > + return 0; > +} > +#endif /* CONFIG_THP_SWAP */ > > static unsigned long scan_swap_map(struct swap_info_struct *si, > unsigned char usage) > @@ -1145,6 +1153,7 @@ void swapcache_free(swp_entry_t entry) > } > } > > +#ifdef CONFIG_THP_SWAP > void swapcache_free_cluster(swp_entry_t entry) > { > unsigned long offset = swp_offset(entry); > @@ -1170,6 +1179,7 @@ void swapcache_free_cluster(swp_entry_t entry) > swap_free_cluster(si, idx); > spin_unlock(&si->lock); > } > +#endif /* CONFIG_THP_SWAP */ > > void swapcache_free_entries(swp_entry_t *entries, int n) > { ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-04-18 0:33 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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[not found] <20170406053515.4842-1-ying.huang@intel.com>
2017-04-06 5:35 ` [PATCH -mm -v8 1/3] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
2017-04-14 14:58 ` Johannes Weiner
2017-04-15 1:17 ` Huang, Ying
2017-04-17 18:24 ` Johannes Weiner
[not found] ` <20170417182410.GA26500-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2017-04-18 0:33 ` Huang, Ying
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