| Message ID | 1558431642-52120-1-git-send-email-yang.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/2] mm: vmscan: remove double slab pressure by inc'ing sc->nr_scanned | expand |
On Tue, May 21, 2019 at 05:40:41PM +0800, Yang Shi wrote: > The commit 9092c71bb724 ("mm: use sc->priority for slab shrink targets") > has broken up the relationship between sc->nr_scanned and slab pressure. > The sc->nr_scanned can't double slab pressure anymore. So, it sounds no > sense to still keep sc->nr_scanned inc'ed. Actually, it would prevent > from adding pressure on slab shrink since excessive sc->nr_scanned would > prevent from scan->priority raise. > > The bonnie test doesn't show this would change the behavior of > slab shrinkers. > > w/ w/o > /sec %CP /sec %CP > Sequential delete: 3960.6 94.6 3997.6 96.2 > Random delete: 2518 63.8 2561.6 64.6 > > The slight increase of "/sec" without the patch would be caused by the > slight increase of CPU usage. > > Cc: Josef Bacik <josef@toxicpanda.com> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c index 7acd0af..b65bc50 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1137,11 +1137,6 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (!sc->may_unmap && page_mapped(page)) goto keep_locked; - /* Double the slab pressure for mapped and swapcache pages */ - if ((page_mapped(page) || PageSwapCache(page)) && - !(PageAnon(page) && !PageSwapBacked(page))) - sc->nr_scanned++; - may_enter_fs = (sc->gfp_mask & __GFP_FS) || (PageSwapCache(page) && (sc->gfp_mask & __GFP_IO));
The commit 9092c71bb724 ("mm: use sc->priority for slab shrink targets") has broken up the relationship between sc->nr_scanned and slab pressure. The sc->nr_scanned can't double slab pressure anymore. So, it sounds no sense to still keep sc->nr_scanned inc'ed. Actually, it would prevent from adding pressure on slab shrink since excessive sc->nr_scanned would prevent from scan->priority raise. The bonnie test doesn't show this would change the behavior of slab shrinkers. w/ w/o /sec %CP /sec %CP Sequential delete: 3960.6 94.6 3997.6 96.2 Random delete: 2518 63.8 2561.6 64.6 The slight increase of "/sec" without the patch would be caused by the slight increase of CPU usage. Cc: Josef Bacik <josef@toxicpanda.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> --- mm/vmscan.c | 5 ----- 1 file changed, 5 deletions(-)