diff options
| author | Michel Lespinasse <walken@google.com> | 2010-10-26 14:21:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-26 16:52:09 -0700 |
| commit | d065bd810b6deb67d4897a14bfe21f8eb526ba99 (patch) | |
| tree | f58c59075732ec4ccba336278c9bdc7ff61bef94 /mm/memory.c | |
| parent | b522c94da5d9cbc73f708be5e530ebc3bbd4a031 (diff) | |
mm: retry page fault when blocking on disk transfer
This change reduces mmap_sem hold times that are caused by waiting for
disk transfers when accessing file mapped VMAs.
It introduces the VM_FAULT_ALLOW_RETRY flag, which indicates that the call
site wants mmap_sem to be released if blocking on a pending disk transfer.
In that case, filemap_fault() returns the VM_FAULT_RETRY status bit and
do_page_fault() will then re-acquire mmap_sem and retry the page fault.
It is expected that the retry will hit the same page which will now be
cached, and thus it will complete with a low mmap_sem hold time.
Tests:
- microbenchmark: thread A mmaps a large file and does random read accesses
to the mmaped area - achieves about 55 iterations/s. Thread B does
mmap/munmap in a loop at a separate location - achieves 55 iterations/s
before, 15000 iterations/s after.
- We are seeing related effects in some applications in house, which show
significant performance regressions when running without this change.
[akpm@linux-foundation.org: fix warning & crash]
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c index 92cc54e94137..714c4438d887 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2627,6 +2627,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, struct page *page, *swapcache = NULL; swp_entry_t entry; pte_t pte; + int locked; struct mem_cgroup *ptr = NULL; int exclusive = 0; int ret = 0; @@ -2677,8 +2678,12 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, goto out_release; } - lock_page(page); + locked = lock_page_or_retry(page, mm, flags); delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + if (!locked) { + ret |= VM_FAULT_RETRY; + goto out_release; + } /* * Make sure try_to_free_swap or reuse_swap_page or swapoff did not @@ -2927,7 +2932,8 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, vmf.page = NULL; ret = vma->vm_ops->fault(vma, &vmf); - if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) + if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | + VM_FAULT_RETRY))) return ret; if (unlikely(PageHWPoison(vmf.page))) { |