Messages in this thread | | | Date | Wed, 1 Jun 2016 15:26:43 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH v2 03/18] mm, page_alloc: don't retry initial attempt in slowpath |
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On Tue 31-05-16 15:08:03, Vlastimil Babka wrote: [...] > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index da3a62a94b4a..9f83259a18a8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3367,10 +3367,9 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > bool drained = false; > > *did_some_progress = __perform_reclaim(gfp_mask, order, ac); > - if (unlikely(!(*did_some_progress))) > - return NULL; > > retry: > + /* We attempt even when no progress, as kswapd might have done some */ > page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac);
Is this really likely to happen, though? Sure we might have last few reclaimable pages on the LRU lists but I am not sure this would make a large difference then.
That being said, I do not think this is harmful but I find it a bit weird to invoke a reclaim and then ignore the feedback... Will leave the decision up to you but the original patch seemed neater.
> > /* > @@ -3378,7 +3377,7 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > * pages are pinned on the per-cpu lists or in high alloc reserves. > * Shrink them them and try again > */ > - if (!page && !drained) { > + if (!page && *did_some_progress && !drained) { > unreserve_highatomic_pageblock(ac); > drain_all_pages(NULL); > drained = true;
I do not remember this in the previous version. Why shouldn't we unreserve highatomic reserves when there was no progress?
-- Michal Hocko SUSE Labs
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