Re: [PATCH 5/5] mm: remove unlikelys for unlock in rmap.c

KOSAKI Motohiro
2009-04-24T11:12:20Z

(cc to lee)

> From: Steven Rostedt <rostedt@goodmis.org>
>
> Impact: clean up
>
> The annotated branch profiler shows that the rmap calls are likely
> called with unlock set.
>
> correct incorrect % Function File Line
> ------- --------- - -------- ---- ----
> 0 46100 100 try_to_unmap_anon rmap.c 1013
> 0 46100 100 try_to_unmap_anon rmap.c 1005
> 0 5763 100 try_to_unmap_file rmap.c 1074
> 0 5763 100 try_to_unmap_file rmap.c 1069
>
> Signed-off-by: Steven Rostedt <srostedt@redhat.com>

unlock==1 mean munlock() is called.
unlock==0 mean memory shortage and reclaim happend.

So, we did guess end-user don't use munlock() so frequently.
but reclaim is frequently happend.

Oh well, but you have rich machine. hmm...
ok, I can agree user can use munlock() frequently.

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

> ---
> mm/rmap.c | 8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 1652166..ad62fe0 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1002,7 +1002,7 @@ static int try_to_unmap_anon(struct page *page, int unlock, int migration)
> unsigned int mlocked = 0;
> int ret = SWAP_AGAIN;
>
> - if (MLOCK_PAGES && unlikely(unlock))
> + if (MLOCK_PAGES && unlock)
> ret = SWAP_SUCCESS; /* default for try_to_munlock() */
>
> anon_vma = page_lock_anon_vma(page);
> @@ -1010,7 +1010,7 @@ static int try_to_unmap_anon(struct page *page, int unlock, int migration)
> return ret;
>
> list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
> - if (MLOCK_PAGES && unlikely(unlock)) {
> + if (MLOCK_PAGES && unlock) {
> if (!((vma->vm_flags & VM_LOCKED) &&
> page_mapped_in_vma(page, vma)))
> continue; /* must visit all unlocked vmas */
> @@ -1066,12 +1066,12 @@ static int try_to_unmap_file(struct page *page, int unlock, int migration)
> unsigned int mapcount;
> unsigned int mlocked = 0;
>
> - if (MLOCK_PAGES && unlikely(unlock))
> + if (MLOCK_PAGES && unlock)
> ret = SWAP_SUCCESS; /* default for try_to_munlock() */
>
> spin_lock(&mapping->i_mmap_lock);
> vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
> - if (MLOCK_PAGES && unlikely(unlock)) {
> + if (MLOCK_PAGES && unlock) {
> if (!((vma->vm_flags & VM_LOCKED) &&
> page_mapped_in_vma(page, vma)))
> continue; /* must visit all vmas */
> --
> 1.6.2
>
> --
> --
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