Messages in this thread | | | Subject | Re: [PATCH 00/14] per memcg lru_lock | From | Daniel Jordan <> | Date | Thu, 22 Aug 2019 11:20:52 -0400 |
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On 8/22/19 7:56 AM, Alex Shi wrote: > 在 2019/8/22 上午2:00, Daniel Jordan 写道: >> https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/tree/case-lru-file-readtwice> >> It's also synthetic but it stresses lru_lock more than just anon alloc/free. It hits the page activate path, which is where we see this lock in our database, and if enough memory is configured lru_lock also gets stressed during reclaim, similar to [1]. > > Thanks for the sharing, this patchset can not help the [1] case, since it's just relief the per container lock contention now.
I should've been clearer. [1] is meant as an example of someone suffering from lru_lock during reclaim. Wouldn't your series help per-memcg reclaim?
> Yes, readtwice case could be more sensitive for this lru_lock changes in containers. I may try to use it in container with some tuning. But anyway, aim9 is also pretty good to show the problem and solutions. :) >> >> It'd be better though, as Michal suggests, to use the real workload that's causing problems. Where are you seeing contention? > > We repeatly create or delete a lot of different containers according to servers load/usage, so normal workload could cause lots of pages alloc/remove.
I think numbers from that scenario would help your case.
> aim9 could reflect part of scenarios. I don't know the DB scenario yet.
We see it during DB shutdown when each DB process frees its memory (zap_pte_range -> mark_page_accessed). But that's a different thing, clearly Not This Series.
>>> With this patch series, lruvec->lru_lock show no contentions >>> &(&lruvec->lru_l... 8 0 0 0 0 0 >>> >>> and aim9 page_test/brk_test performance increased 5%~50%. >> >> Where does the 50% number come in? The numbers below seem to only show ~4% boost. > > the Setddev/CoeffVar case has about 50% performance increase. one of container's mmtests result as following: > > Stddev page_test 245.15 ( 0.00%) 189.29 ( 22.79%) > Stddev brk_test 1258.60 ( 0.00%) 629.16 ( 50.01%) > CoeffVar page_test 0.71 ( 0.00%) 0.53 ( 26.05%) > CoeffVar brk_test 1.32 ( 0.00%) 0.64 ( 51.14%)
Aha. 50% decrease in stdev.
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