[RFC PATCH] LTTng instrumentation mm (updated)

Mathieu Desnoyers
2007-11-30T16:12:16Z

LTTng instrumentation mm

Memory management core events.

Changelog:
- Use page_to_pfn for swap out instrumentation, wait_on_page_bit, do_swap_page,
page alloc/free.
- add missing free_hot_cold_page instrumentation.
- add hugetlb page_alloc page_free instrumentation.
- Add write_access to mm fault.
- Add page bit_nr waited for by wait_on_page_bit.
- Move page alloc instrumentation to __aloc_pages so we cover the alloc zeroed
page path.
- Add swap file used for swap in and swap out events.
- Dump the swap files, instrument swapon and swapoff.

(note : I did not change the other sites where page_swp_entry could be
used)
(note 2 : my FS instrumentation does not dump the kernel vfs mounts,
which would be useful to interpret the "dump swap files"
instrumentation. I should add this eventually.)

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: linux-mm@kvack.org
CC: Dave Hansen <haveblue@us.ibm.com>
---
include/linux/swapops.h | 8 ++++++++
mm/filemap.c | 6 ++++++
mm/hugetlb.c | 2 ++
mm/memory.c | 38 +++++++++++++++++++++++++++++---------
mm/page_alloc.c | 6 ++++++
mm/page_io.c | 5 +++++
mm/swapfile.c | 22 ++++++++++++++++++++++
7 files changed, 78 insertions(+), 9 deletions(-)

Index: linux-2.6-lttng/mm/filemap.c
===================================================================
--- linux-2.6-lttng.orig/mm/filemap.c 2007-11-29 20:22:52.000000000 -0500
+++ linux-2.6-lttng/mm/filemap.c 2007-11-29 20:23:01.000000000 -0500
@@ -514,9 +514,15 @@ void fastcall wait_on_page_bit(struct pa
{
DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);

+ trace_mark(mm_filemap_wait_start, "pfn %lu bit_nr %d",
+ page_to_pfn(page), bit_nr);
+
if (test_bit(bit_nr, &page->flags))
__wait_on_bit(page_waitqueue(page), &wait, sync_page,
TASK_UNINTERRUPTIBLE);
+
+ trace_mark(mm_filemap_wait_end, "pfn %lu bit_nr %d",
+ page_to_pfn(page), bit_nr);
}
EXPORT_SYMBOL(wait_on_page_bit);

Index: linux-2.6-lttng/mm/memory.c
===================================================================
--- linux-2.6-lttng.orig/mm/memory.c 2007-11-29 20:22:52.000000000 -0500
+++ linux-2.6-lttng/mm/memory.c 2007-11-29 20:42:36.000000000 -0500
@@ -2090,6 +2090,10 @@ static int do_swap_page(struct mm_struct
/* Had to read the page from swap area: Major fault */
ret = VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
+ trace_mark(mm_swap_in, "pfn %lu filp %p offset %lu",
+ page_to_pfn(page),
+ get_swap_info_struct(swp_type(entry))->swap_file,
+ swp_offset(entry));
}

mark_page_accessed(page);
@@ -2526,30 +2530,46 @@ unlock:
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, int write_access)
{
+ int res;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;

+ trace_mark(mm_handle_fault_entry,
+ "address %lu ip #p%ld write_access %d",
+ address, KSTK_EIP(current), write_access);
+
__set_current_state(TASK_RUNNING);

count_vm_event(PGFAULT);

- if (unlikely(is_vm_hugetlb_page(vma)))
- return hugetlb_fault(mm, vma, address, write_access);
+ if (unlikely(is_vm_hugetlb_page(vma))) {
+ res = hugetlb_fault(mm, vma, address, write_access);
+ goto end;
+ }

pgd = pgd_offset(mm, address);
pud = pud_alloc(mm, pgd, address);
- if (!pud)
- return VM_FAULT_OOM;
+ if (!pud) {
+ res = VM_FAULT_OOM;
+ goto end;
+ }
pmd = pmd_alloc(mm, pud, address);
- if (!pmd)
- return VM_FAULT_OOM;
+ if (!pmd) {
+ res = VM_FAULT_OOM;
+ goto end;
+ }
pte = pte_alloc_map(mm, pmd, address);
- if (!pte)
- return VM_FAULT_OOM;
+ if (!pte) {
+ res = VM_FAULT_OOM;
+ goto end;
+ }

- return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
+ res = handle_pte_fault(mm, vma, address, pte, pmd, write_access);
+end:
+ trace_mark(mm_handle_fault_exit, MARK_NOARGS);
+ return res;
}

#ifndef __PAGETABLE_PUD_FOLDED
Index: linux-2.6-lttng/mm/page_alloc.c
===================================================================
--- linux-2.6-lttng.orig/mm/page_alloc.c 2007-11-29 20:22:52.000000000 -0500
+++ linux-2.6-lttng/mm/page_alloc.c 2007-11-29 20:23:01.000000000 -0500
@@ -519,6 +519,9 @@ static void __free_pages_ok(struct page
int i;
int reserved = 0;

+ trace_mark(mm_page_free, "order %u pfn %lu",
+ order, page_to_pfn(page));
+
for (i = 0 ; i < (1 << order) ; ++i)
reserved += free_pages_check(page + i);
if (reserved)
@@ -981,6 +984,8 @@ static void fastcall free_hot_cold_page(
struct per_cpu_pages *pcp;
unsigned long flags;

+ trace_mark(mm_page_free, "order %u pfn %lu", 0, page_to_pfn(page));
+
if (PageAnon(page))
page->mapping = NULL;
if (free_pages_check(page))
@@ -1625,6 +1630,7 @@ nopage:
show_mem();
}
got_pg:
+ trace_mark(mm_page_alloc, "order %u pfn %lu", order, page_to_pfn(page));
return page;
}

Index: linux-2.6-lttng/mm/page_io.c
===================================================================
--- linux-2.6-lttng.orig/mm/page_io.c 2007-11-29 20:22:52.000000000 -0500
+++ linux-2.6-lttng/mm/page_io.c 2007-11-29 20:43:02.000000000 -0500
@@ -114,6 +114,11 @@ int swap_writepage(struct page *page, st
rw |= (1 << BIO_RW_SYNC);
count_vm_event(PSWPOUT);
set_page_writeback(page);
+ trace_mark(mm_swap_out, "pfn %lu filp %p offset %lu",
+ page_to_pfn(page),
+ get_swap_info_struct(swp_type(
+ page_swp_entry(page)))->swap_file,
+ swp_offset(page_swp_entry(page)));
unlock_page(page);
submit_bio(rw, bio);
out:
Index: linux-2.6-lttng/mm/hugetlb.c
===================================================================
--- linux-2.6-lttng.orig/mm/hugetlb.c 2007-11-29 20:22:52.000000000 -0500
+++ linux-2.6-lttng/mm/hugetlb.c 2007-11-29 20:23:01.000000000 -0500
@@ -118,6 +118,7 @@ static void free_huge_page(struct page *
int nid = page_to_nid(page);
struct address_space *mapping;

+ trace_mark(mm_huge_page_free, "pfn %lu", page_to_pfn(page));
mapping = (struct address_space *) page_private(page);
BUG_ON(page_count(page));
INIT_LIST_HEAD(&page->lru);
@@ -401,6 +402,7 @@ static struct page *alloc_huge_page(stru
if (!IS_ERR(page)) {
set_page_refcounted(page);
set_page_private(page, (unsigned long) mapping);
+ trace_mark(mm_huge_page_alloc, "pfn %lu", page_to_pfn(page));
}
return page;
}
Index: linux-2.6-lttng/include/linux/swapops.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/swapops.h 2007-11-29 20:22:52.000000000 -0500
+++ linux-2.6-lttng/include/linux/swapops.h 2007-11-29 20:23:01.000000000 -0500
@@ -68,6 +68,14 @@ static inline pte_t swp_entry_to_pte(swp
return __swp_entry_to_pte(arch_entry);
}

+static inline swp_entry_t page_swp_entry(struct page *page)
+{
+ swp_entry_t entry;
+ VM_BUG_ON(!PageSwapCache(page));
+ entry.val = page_private(page);
+ return entry;
+}
+
#ifdef CONFIG_MIGRATION
static inline swp_entry_t make_migration_entry(struct page *page, int write)
{
Index: linux-2.6-lttng/mm/swapfile.c
===================================================================
--- linux-2.6-lttng.orig/mm/swapfile.c 2007-11-30 09:18:38.000000000 -0500
+++ linux-2.6-lttng/mm/swapfile.c 2007-11-30 10:21:50.000000000 -0500
@@ -1279,6 +1279,7 @@ asmlinkage long sys_swapoff(const char _
swap_map = p->swap_map;
p->swap_map = NULL;
p->flags = 0;
+ trace_mark(mm_swap_file_close, "filp %p", swap_file);
spin_unlock(&swap_lock);
mutex_unlock(&swapon_mutex);
vfree(swap_map);
@@ -1660,6 +1661,8 @@ asmlinkage long sys_swapon(const char __
} else {
swap_info[prev].next = p - swap_info;
}
+ trace_mark(mm_swap_file_open, "filp %p filename %s",
+ swap_file, name);
spin_unlock(&swap_lock);
mutex_unlock(&swapon_mutex);
error = 0;
@@ -1796,3 +1799,22 @@ int valid_swaphandles(swp_entry_t entry,
spin_unlock(&swap_lock);
return ret;
}
+
+void ltt_dump_swap_files(void *call_data)
+{
+ int type;
+ struct swap_info_struct * p = NULL;
+
+ mutex_lock(&swapon_mutex);
+ for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
+ p = swap_info + type;
+ if ((p->flags & SWP_ACTIVE) != SWP_ACTIVE)
+ continue;
+ __trace_mark(0, statedump_swap_files, call_data,
+ "filp %p vfsmount %p dname %s",
+ p->swap_file, p->swap_file->f_vfsmnt,
+ p->swap_file->f_dentry->d_name.name);
+ }
+ mutex_unlock(&swapon_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_dump_swap_files);