Messages in this thread | | | Date | Wed, 24 Aug 2022 17:33:30 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2 2/3] mm: page_counter: rearrange struct page_counter fields |
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On Thu, 25 Aug 2022 00:05:05 +0000 Shakeel Butt <shakeelb@google.com> wrote:
> With memcg v2 enabled, memcg->memory.usage is a very hot member for > the workloads doing memcg charging on multiple CPUs concurrently. > Particularly the network intensive workloads. In addition, there is a > false cache sharing between memory.usage and memory.high on the charge > path. This patch moves the usage into a separate cacheline and move all > the read most fields into separate cacheline. > > To evaluate the impact of this optimization, on a 72 CPUs machine, we > ran the following workload in a three level of cgroup hierarchy. > > $ netserver -6 > # 36 instances of netperf with following params > $ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K > > Results (average throughput of netperf): > Without (6.0-rc1) 10482.7 Mbps > With patch 12413.7 Mbps (18.4% improvement) > > With the patch, the throughput improved by 18.4%. > > One side-effect of this patch is the increase in the size of struct > mem_cgroup. For example with this patch on 64 bit build, the size of > struct mem_cgroup increased from 4032 bytes to 4416 bytes. However for > the performance improvement, this additional size is worth it. In > addition there are opportunities to reduce the size of struct > mem_cgroup like deprecation of kmem and tcpmem page counters and > better packing.
Did you evaluate the effects of using a per-cpu counter of some form?
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