On Thu 22-09-16 16:08:21, Michal Hocko wrote:
> On Thu 22-09-16 14:51:48, Vlastimil Babka wrote:
> > >From 465e1bd61b7a6d6901a44f09b1a76514dbc220fa Mon Sep 17 00:00:00 2001
> > From: Vlastimil Babka <vba...@suse.cz>
> > Date: Thu, 22 Sep 2016 13:54:32 +0200
> > Subject: [PATCH] mm, compaction: more reliably increase direct compaction
> > priority-fix
> >
> > When increasing the compaction priority, also reset retries. Otherwise we
> > can
> > consume all retries on the lower priorities.
>
> OK, this is an improvement. I am just thinking that we might want to
> pull
> if (order && compaction_made_progress(compact_result))
> compaction_retries++;
>
> into should_compact_retry as well. I've had it there originally because
> it was in line with no_progress_loops but now that we have compaction
> priorities it would fit into retry logic better. As a plus it would
> count only those compaction rounds where we we didn't have to rely on
did that should be
> the compaction retry logic. What do you think?
>
> > Suggested-by: Michal Hocko <mho...@suse.com>
> > Signed-off-by: Vlastimil Babka <vba...@suse.cz>
>
> Anyway
> Acked-by: Michal Hocko <mho...@suse.com>
>
> > ---
> > mm/page_alloc.c | 13 +++++++------
> > 1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index f8bed910e3cf..82fdb690ac62 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -3162,7 +3162,7 @@ static inline bool
> > should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
> > enum compact_result compact_result,
> > enum compact_priority *compact_priority,
> > - int compaction_retries)
> > + int *compaction_retries)
> > {
> > int max_retries = MAX_COMPACT_RETRIES;
> >
> > @@ -3196,16 +3196,17 @@ should_compact_retry(struct alloc_context *ac, int
> > order, int alloc_flags,
> > */
> > if (order > PAGE_ALLOC_COSTLY_ORDER)
> > max_retries /= 4;
> > - if (compaction_retries <= max_retries)
> > + if (*compaction_retries <= max_retries)
> > return true;
> >
> > /*
> > - * Make sure there is at least one attempt at the highest priority
> > - * if we exhausted all retries at the lower priorities
> > + * Make sure there are attempts at the highest priority if we exhausted
> > + * all retries or failed at the lower priorities.
> > */
> > check_priority:
> > if (*compact_priority > MIN_COMPACT_PRIORITY) {
> > (*compact_priority)--;
> > + *compaction_retries = 0;
> > return true;
> > }
> > return false;
> > @@ -3224,7 +3225,7 @@ static inline bool
> > should_compact_retry(struct alloc_context *ac, unsigned int order, int
> > alloc_flags,
> > enum compact_result compact_result,
> > enum compact_priority *compact_priority,
> > - int compaction_retries)
> > + int *compaction_retries)
> > {
> > struct zone *zone;
> > struct zoneref *z;
> > @@ -3663,7 +3664,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int
> > order,
> > if (did_some_progress > 0 &&
> > should_compact_retry(ac, order, alloc_flags,
> > compact_result, &compact_priority,
> > - compaction_retries))
> > + &compaction_retries))
> > goto retry;
> >
> > /* Reclaim has failed us, start killing things */
> > --
> > 2.10.0
> >
>
> --
> Michal Hocko
> SUSE Labs
--
Michal Hocko
SUSE Labs
