Messages in this thread | | | Subject | Re: [RFC 12/13] mm, compaction: more reliably increase direct compaction priority | From | Vlastimil Babka <> | Date | Tue, 31 May 2016 14:29:24 +0200 |
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On 05/31/2016 02:07 PM, Vlastimil Babka wrote: > On 05/31/2016 08:37 AM, Joonsoo Kim wrote: >>> @@ -3695,22 +3695,22 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, >>> else >>> no_progress_loops++; >>> >>> - if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, >>> - did_some_progress > 0, no_progress_loops)) >>> - goto retry; >>> - >>> + should_retry = should_reclaim_retry(gfp_mask, order, ac, alloc_flags, >>> + did_some_progress > 0, no_progress_loops); >>> /* >>> * It doesn't make any sense to retry for the compaction if the order-0 >>> * reclaim is not able to make any progress because the current >>> * implementation of the compaction depends on the sufficient amount >>> * of free memory (see __compaction_suitable) >>> */ >>> - if (did_some_progress > 0 && >>> - should_compact_retry(ac, order, alloc_flags, >>> + if (did_some_progress > 0) >>> + should_retry |= should_compact_retry(ac, order, alloc_flags, >>> compact_result, &compact_priority, >>> - compaction_retries)) >>> + compaction_retries); >>> + if (should_retry) >>> goto retry; >> >> Hmm... it looks odd that we check should_compact_retry() when >> did_some_progress > 0. If system is full of anonymous memory and we >> don't have swap, we can't reclaim anything but we can compact. > > Right, thanks.
Hmm on the other hand, should_compact_retry will assume (in compaction_zonelist_suitable()) that reclaimable memory is actually reclaimable. If there's nothing to tell us that it actually isn't, if we drop the reclaim progress requirement. That's risking an infinite loop?
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