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> > > > + int batch = READ_ONCE(pcp->batch); > > > > > > > > - if (unlikely(!high || free_high)) > > > > + if (unlikely(!high)) > > > > return 0; > > > > > > > > - if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags)) > > > > - return high; > > > > - > > > > /* > > > > * If reclaim is active, limit the number of pages that can be > > > > * stored on pcp lists > > > > */ > > > > - return min(READ_ONCE(pcp->batch) << 2, high); > > > > + if (test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags) || free_high) > > > > + return min(batch << 2, high); > > > > + > > > > + return high; > > > > } > > > > > > > > static void free_unref_page_commit(struct page *page, int migratetype, > > > > > > > > Does this look sane? If so, I can prepare a formal patch with proper > > > > comment and changelog, thanks. > > > > > > I think it looks reasonable sane. The corner case is that if > > > ((high - (batch >> 2)) > cachesize) that the pages will not get recycled > > > > When free_high is true, the above diff changed the return value of > > nr_pcp_high() from 0 to min(batch << 2, pcp->high) so the corner case is > > when (min(batch << 2, pcp->high) > cachesize)? > > > > Yes. It's not perfect due to cache aliasing so the actual point where it > matters will be variable. Whatever the value is, there a value where the > corner case applies that pages do not get recycled quickly enough and > are no longer cache-hot. Understood. And as you said, it's a tradeoff.