[RFC3 04/14] Convert nr_pagecache

Christoph Lameter
2005-12-15T00:14:35Z

Convert nr_pagecache a zoned counter

Currently a single atomic variable is used to establish the size of the page cache
in the whole machine. The zoned VM counters have the same method of implementation
as the nr_pagecache code. Remove the special implementation for nr_pagecache and make
it a zoned counter. We will then be able to figure out how much of the memory in a
zone is used by the pagecache.

Updates of the page cache counters are always performed with interrupts off.
We can therefore use the __ variant here.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.15-rc5-mm2/include/linux/pagemap.h
===================================================================
--- linux-2.6.15-rc5-mm2.orig/include/linux/pagemap.h 2005-12-12 09:10:34.000000000 -0800
+++ linux-2.6.15-rc5-mm2/include/linux/pagemap.h 2005-12-14 14:57:33.000000000 -0800
@@ -99,51 +99,6 @@ int add_to_page_cache_lru(struct page *p
extern void remove_from_page_cache(struct page *page);
extern void __remove_from_page_cache(struct page *page);

-extern atomic_t nr_pagecache;
-
-#ifdef CONFIG_SMP
-
-#define PAGECACHE_ACCT_THRESHOLD max(16, NR_CPUS * 2)
-DECLARE_PER_CPU(long, nr_pagecache_local);
-
-/*
- * pagecache_acct implements approximate accounting for pagecache.
- * vm_enough_memory() do not need high accuracy. Writers will keep
- * an offset in their per-cpu arena and will spill that into the
- * global count whenever the absolute value of the local count
- * exceeds the counter's threshold.
- *
- * MUST be protected from preemption.
- * current protection is mapping->page_lock.
- */
-static inline void pagecache_acct(int count)
-{
- long *local;
-
- local = &__get_cpu_var(nr_pagecache_local);
- *local += count;
- if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) {
- atomic_add(*local, &nr_pagecache);
- *local = 0;
- }
-}
-
-#else
-
-static inline void pagecache_acct(int count)
-{
- atomic_add(count, &nr_pagecache);
-}
-#endif
-
-static inline unsigned long get_page_cache_size(void)
-{
- int ret = atomic_read(&nr_pagecache);
- if (unlikely(ret < 0))
- ret = 0;
- return ret;
-}
-
/*
* Return byte-offset into filesystem object for page.
*/
Index: linux-2.6.15-rc5-mm2/mm/swap_state.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/mm/swap_state.c 2005-12-13 20:41:05.000000000 -0800
+++ linux-2.6.15-rc5-mm2/mm/swap_state.c 2005-12-14 14:57:33.000000000 -0800
@@ -87,7 +87,7 @@ static int __add_to_swap_cache(struct pa
SetPageSwapCache(page);
set_page_private(page, entry.val);
total_swapcache_pages++;
- pagecache_acct(1);
+ __inc_zone_page_state(page, NR_PAGECACHE);
}
write_unlock_irq(&swapper_space.tree_lock);
radix_tree_preload_end();
@@ -133,7 +133,7 @@ void __delete_from_swap_cache(struct pag
set_page_private(page, 0);
ClearPageSwapCache(page);
total_swapcache_pages--;
- pagecache_acct(-1);
+ __dec_zone_page_state(page, NR_PAGECACHE);
INC_CACHE_INFO(del_total);
}

Index: linux-2.6.15-rc5-mm2/mm/filemap.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/mm/filemap.c 2005-12-12 09:10:34.000000000 -0800
+++ linux-2.6.15-rc5-mm2/mm/filemap.c 2005-12-14 14:57:33.000000000 -0800
@@ -115,7 +115,7 @@ void __remove_from_page_cache(struct pag
radix_tree_delete(&mapping->page_tree, page->index);
page->mapping = NULL;
mapping->nrpages--;
- pagecache_acct(-1);
+ __dec_zone_page_state(page, NR_PAGECACHE);
}
EXPORT_SYMBOL(__remove_from_page_cache);

@@ -406,7 +406,7 @@ int add_to_page_cache(struct page *page,
page->mapping = mapping;
page->index = offset;
mapping->nrpages++;
- pagecache_acct(1);
+ __inc_zone_page_state(page, NR_PAGECACHE);
}
write_unlock_irq(&mapping->tree_lock);
radix_tree_preload_end();
Index: linux-2.6.15-rc5-mm2/mm/page_alloc.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/mm/page_alloc.c 2005-12-14 14:57:29.000000000 -0800
+++ linux-2.6.15-rc5-mm2/mm/page_alloc.c 2005-12-14 14:57:33.000000000 -0800
@@ -1578,12 +1578,6 @@ static void show_node(struct zone *zone)
*/
static DEFINE_PER_CPU(struct page_state, page_states) = {0};

-atomic_t nr_pagecache = ATOMIC_INIT(0);
-EXPORT_SYMBOL(nr_pagecache);
-#ifdef CONFIG_SMP
-DEFINE_PER_CPU(long, nr_pagecache_local) = 0;
-#endif
-
static void __get_page_state(struct page_state *ret, int nr, cpumask_t *cpumask)
{
int cpu = 0;
Index: linux-2.6.15-rc5-mm2/mm/mmap.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/mm/mmap.c 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5-mm2/mm/mmap.c 2005-12-14 14:57:33.000000000 -0800
@@ -95,7 +95,7 @@ int __vm_enough_memory(long pages, int c
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
unsigned long n;

- free = get_page_cache_size();
+ free = global_page_state(NR_PAGECACHE);
free += nr_swap_pages;

/*
Index: linux-2.6.15-rc5-mm2/mm/nommu.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/mm/nommu.c 2005-12-12 09:10:34.000000000 -0800
+++ linux-2.6.15-rc5-mm2/mm/nommu.c 2005-12-14 14:57:33.000000000 -0800
@@ -1114,7 +1114,7 @@ int __vm_enough_memory(long pages, int c
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
unsigned long n;

- free = get_page_cache_size();
+ free = global_page_state(NR_PAGECACHE);
free += nr_swap_pages;

/*
Index: linux-2.6.15-rc5-mm2/arch/sparc64/kernel/sys_sunos32.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/arch/sparc64/kernel/sys_sunos32.c 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5-mm2/arch/sparc64/kernel/sys_sunos32.c 2005-12-14 14:57:33.000000000 -0800
@@ -154,7 +154,7 @@ asmlinkage int sunos_brk(u32 baddr)
* simple, it hopefully works in most obvious cases.. Easy to
* fool it, but this should catch most mistakes.
*/
- freepages = get_page_cache_size();
+ freepages = global_page_state(NR_PAGECACHE);
freepages >>= 1;
freepages += nr_free_pages();
freepages += nr_swap_pages;
Index: linux-2.6.15-rc5-mm2/arch/sparc/kernel/sys_sunos.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/arch/sparc/kernel/sys_sunos.c 2005-12-03 21:10:42.000000000 -0800
+++ linux-2.6.15-rc5-mm2/arch/sparc/kernel/sys_sunos.c 2005-12-14 14:57:33.000000000 -0800
@@ -195,7 +195,7 @@ asmlinkage int sunos_brk(unsigned long b
* simple, it hopefully works in most obvious cases.. Easy to
* fool it, but this should catch most mistakes.
*/
- freepages = get_page_cache_size();
+ freepages = global_page_state(NR_PAGECACHE);
freepages >>= 1;
freepages += nr_free_pages();
freepages += nr_swap_pages;
Index: linux-2.6.15-rc5-mm2/fs/proc/proc_misc.c
===================================================================
--- linux-2.6.15-rc5-mm2.orig/fs/proc/proc_misc.c 2005-12-14 14:57:29.000000000 -0800
+++ linux-2.6.15-rc5-mm2/fs/proc/proc_misc.c 2005-12-14 14:57:33.000000000 -0800
@@ -142,7 +142,7 @@ static int meminfo_read_proc(char *page,
allowed = ((totalram_pages - hugetlb_total_pages())
* sysctl_overcommit_ratio / 100) + total_swap_pages;

- cached = get_page_cache_size() - total_swapcache_pages - i.bufferram;
+ cached = global_page_state(NR_PAGECACHE) - total_swapcache_pages - i.bufferram;
if (cached < 0)
cached = 0;

Index: linux-2.6.15-rc5-mm2/include/linux/mmzone.h
===================================================================
--- linux-2.6.15-rc5-mm2.orig/include/linux/mmzone.h 2005-12-14 14:57:29.000000000 -0800
+++ linux-2.6.15-rc5-mm2/include/linux/mmzone.h 2005-12-14 14:57:33.000000000 -0800
@@ -44,8 +44,8 @@ struct zone_padding {
#define ZONE_PADDING(name)
#endif

-enum zone_stat_item { NR_MAPPED };
-#define NR_STAT_ITEMS 1
+enum zone_stat_item { NR_MAPPED, NR_PAGECACHE };
+#define NR_STAT_ITEMS 2

struct per_cpu_pages {
int count; /* number of pages in the list */