Messages in this thread | | | Subject | Re: [RFC PATCH 3/5] mm/page_alloc: stop instantly reusing freed page | From | Vlastimil Babka <> | Date | Thu, 13 Oct 2016 12:59:14 +0200 |
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On 10/13/2016 10:08 AM, js1304@gmail.com wrote: > From: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > Allocation/free pattern is usually sequantial. If they are freed to > the buddy list, they can be coalesced. However, we first keep these freed > pages at the pcp list and try to reuse them until threshold is reached > so we don't have enough chance to get a high order freepage. This reusing > would provide us some performance advantages since we don't need to > get the zone lock and we don't pay the cost to check buddy merging. > But, less fragmentation and more high order freepage would compensate > this overhead in other ways. First, we would trigger less direct > compaction which has high overhead. And, there are usecases that uses > high order page to boost their performance. > > Instantly resuing freed page seems to provide us computational benefit > but the other affects more precious things like as I/O performance and > memory consumption so I think that it's a good idea to weight > later advantage more.
Again, there's also cache hotness to consider. And whether the sequential pattern is still real on a system with higher uptime. Should be possible to evaluate with tracepoints?
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