From: Eric Dumazet <edumazet@google.com> To: Shakeel Butt <shakeelb@google.com> Cc: Feng Tang <feng.tang@intel.com>, Linux MM <linux-mm@kvack.org>, Andrew Morton <akpm@linux-foundation.org>, Roman Gushchin <roman.gushchin@linux.dev>, Michal Hocko <mhocko@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>, Muchun Song <songmuchun@bytedance.com>, Jakub Kicinski <kuba@kernel.org>, Xin Long <lucien.xin@gmail.com>, Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>, kernel test robot <oliver.sang@intel.com>, Soheil Hassas Yeganeh <soheil@google.com>, LKML <linux-kernel@vger.kernel.org>, network dev <netdev@vger.kernel.org>, linux-s390@vger.kernel.org, MPTCP Upstream <mptcp@lists.linux.dev>, "linux-sctp @ vger . kernel . org" <linux-sctp@vger.kernel.org>, lkp@lists.01.org, kbuild test robot <lkp@intel.com>, Huang Ying <ying.huang@intel.com>, Xing Zhengjun <zhengjun.xing@linux.intel.com>, Yin Fengwei <fengwei.yin@intel.com>, Ying Xu <yinxu@redhat.com> Subject: Re: [net] 4890b686f4: netperf.Throughput_Mbps -69.4% regression Date: Mon, 27 Jun 2022 19:05:17 +0200 [thread overview] Message-ID: <CANn89iLnOBGk+P33MRAkNwVLQC+s1M36m+cg1d4pJ970ecdxcg@mail.gmail.com> (raw) In-Reply-To: <CALvZod60OHC4iQnyBd16evCHXa_8ucpHiRnm9iNErQeUOycGZw@mail.gmail.com> On Mon, Jun 27, 2022 at 6:48 PM Shakeel Butt <shakeelb@google.com> wrote: > > On Mon, Jun 27, 2022 at 9:26 AM Eric Dumazet <edumazet@google.com> wrote: > > > [...] > > > > > > > I simply did the following and got much better results. > > > > But I am not sure if updates to ->usage are really needed that often... > > I suspect we need to improve the per-cpu memcg stock usage here. Were > the updates mostly from uncharge path or charge path or that's > irrelevant? I wonder if the cache is always used... stock = this_cpu_ptr(&memcg_stock); if (memcg == stock->cached && stock->nr_pages >= nr_pages) { Apparently the per-cpu cache is only used for one memcg at a time ? Not sure how this would scale to hosts with dozens of memcgs. Maybe we could add some metrics to have an idea of the cache hit/miss ratio :/ > > I think doing full drain (i.e. drain_stock()) within __refill_stock() > when the local cache is larger than MEMCG_CHARGE_BATCH is not best. > Rather we should always keep at least MEMCG_CHARGE_BATCH for such > scenarios. > > > > > > > diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h > > index 679591301994d316062f92b275efa2459a8349c9..e267be4ba849760117d9fd041e22c2a44658ab36 > > 100644 > > --- a/include/linux/page_counter.h > > +++ b/include/linux/page_counter.h > > @@ -3,12 +3,15 @@ > > #define _LINUX_PAGE_COUNTER_H > > > > #include <linux/atomic.h> > > +#include <linux/cache.h> > > #include <linux/kernel.h> > > #include <asm/page.h> > > > > struct page_counter { > > - atomic_long_t usage; > > - unsigned long min; > > + /* contended cache line. */ > > + atomic_long_t usage ____cacheline_aligned_in_smp; > > + > > + unsigned long min ____cacheline_aligned_in_smp; > > Do we need to align 'min' too? Probably if there is a hierarchy ... propagate_protected_usage() seems to have potential high cost. > > > unsigned long low; > > unsigned long high; > > unsigned long max; > > @@ -27,12 +30,6 @@ struct page_counter { > > unsigned long watermark; > > unsigned long failcnt; > > > > - /* > > - * 'parent' is placed here to be far from 'usage' to reduce > > - * cache false sharing, as 'usage' is written mostly while > > - * parent is frequently read for cgroup's hierarchical > > - * counting nature. > > - */ > > struct page_counter *parent; > > }; > > > > > >
WARNING: multiple messages have this Message-ID (diff)
From: Eric Dumazet <edumazet@google.com> To: lkp@lists.01.org Subject: Re: [net] 4890b686f4: netperf.Throughput_Mbps -69.4% regression Date: Mon, 27 Jun 2022 19:05:17 +0200 [thread overview] Message-ID: <CANn89iLnOBGk+P33MRAkNwVLQC+s1M36m+cg1d4pJ970ecdxcg@mail.gmail.com> (raw) In-Reply-To: <CALvZod60OHC4iQnyBd16evCHXa_8ucpHiRnm9iNErQeUOycGZw@mail.gmail.com> [-- Attachment #1: Type: text/plain, Size: 2527 bytes --] On Mon, Jun 27, 2022 at 6:48 PM Shakeel Butt <shakeelb@google.com> wrote: > > On Mon, Jun 27, 2022 at 9:26 AM Eric Dumazet <edumazet@google.com> wrote: > > > [...] > > > > > > > I simply did the following and got much better results. > > > > But I am not sure if updates to ->usage are really needed that often... > > I suspect we need to improve the per-cpu memcg stock usage here. Were > the updates mostly from uncharge path or charge path or that's > irrelevant? I wonder if the cache is always used... stock = this_cpu_ptr(&memcg_stock); if (memcg == stock->cached && stock->nr_pages >= nr_pages) { Apparently the per-cpu cache is only used for one memcg at a time ? Not sure how this would scale to hosts with dozens of memcgs. Maybe we could add some metrics to have an idea of the cache hit/miss ratio :/ > > I think doing full drain (i.e. drain_stock()) within __refill_stock() > when the local cache is larger than MEMCG_CHARGE_BATCH is not best. > Rather we should always keep at least MEMCG_CHARGE_BATCH for such > scenarios. > > > > > > > diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h > > index 679591301994d316062f92b275efa2459a8349c9..e267be4ba849760117d9fd041e22c2a44658ab36 > > 100644 > > --- a/include/linux/page_counter.h > > +++ b/include/linux/page_counter.h > > @@ -3,12 +3,15 @@ > > #define _LINUX_PAGE_COUNTER_H > > > > #include <linux/atomic.h> > > +#include <linux/cache.h> > > #include <linux/kernel.h> > > #include <asm/page.h> > > > > struct page_counter { > > - atomic_long_t usage; > > - unsigned long min; > > + /* contended cache line. */ > > + atomic_long_t usage ____cacheline_aligned_in_smp; > > + > > + unsigned long min ____cacheline_aligned_in_smp; > > Do we need to align 'min' too? Probably if there is a hierarchy ... propagate_protected_usage() seems to have potential high cost. > > > unsigned long low; > > unsigned long high; > > unsigned long max; > > @@ -27,12 +30,6 @@ struct page_counter { > > unsigned long watermark; > > unsigned long failcnt; > > > > - /* > > - * 'parent' is placed here to be far from 'usage' to reduce > > - * cache false sharing, as 'usage' is written mostly while > > - * parent is frequently read for cgroup's hierarchical > > - * counting nature. > > - */ > > struct page_counter *parent; > > }; > > > > > >
next prev parent reply other threads:[~2022-06-27 17:05 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-06-19 15:04 [net] 4890b686f4: netperf.Throughput_Mbps -69.4% regression kernel test robot 2022-06-19 15:04 ` kernel test robot 2022-06-23 0:28 ` Jakub Kicinski 2022-06-23 0:28 ` Jakub Kicinski 2022-06-23 3:08 ` Xin Long 2022-06-23 3:08 ` Xin Long 2022-06-23 22:50 ` Xin Long 2022-06-23 22:50 ` Xin Long 2022-06-24 1:57 ` Jakub Kicinski 2022-06-24 1:57 ` Jakub Kicinski 2022-06-24 4:13 ` Eric Dumazet 2022-06-24 4:13 ` Eric Dumazet 2022-06-24 4:22 ` Eric Dumazet 2022-06-24 4:22 ` Eric Dumazet 2022-06-24 5:13 ` Feng Tang 2022-06-24 5:13 ` Feng Tang 2022-06-24 5:45 ` Eric Dumazet 2022-06-24 5:45 ` Eric Dumazet 2022-06-24 6:00 ` Feng Tang 2022-06-24 6:00 ` Feng Tang 2022-06-24 6:07 ` Eric Dumazet 2022-06-24 6:07 ` Eric Dumazet 2022-06-24 6:34 ` Shakeel Butt 2022-06-24 6:34 ` Shakeel Butt 2022-06-24 7:06 ` Feng Tang 2022-06-24 7:06 ` Feng Tang 2022-06-24 14:43 ` Shakeel Butt 2022-06-24 14:43 ` Shakeel Butt 2022-06-25 2:36 ` Feng Tang 2022-06-25 2:36 ` Feng Tang 2022-06-27 2:38 ` Feng Tang 2022-06-27 2:38 ` Feng Tang 2022-06-27 8:46 ` Eric Dumazet 2022-06-27 8:46 ` Eric Dumazet 2022-06-27 12:34 ` Feng Tang 2022-06-27 12:34 ` Feng Tang 2022-06-27 14:07 ` Eric Dumazet 2022-06-27 14:07 ` Eric Dumazet 2022-06-27 14:48 ` Feng Tang 2022-06-27 14:48 ` Feng Tang 2022-06-27 16:25 ` Eric Dumazet 2022-06-27 16:25 ` Eric Dumazet 2022-06-27 16:48 ` Shakeel Butt 2022-06-27 16:48 ` Shakeel Butt 2022-06-27 17:05 ` Eric Dumazet [this message] 2022-06-27 17:05 ` Eric Dumazet 2022-06-28 1:46 ` Roman Gushchin 2022-06-28 1:46 ` Roman Gushchin 2022-06-28 3:49 ` Feng Tang 2022-06-28 3:49 ` Feng Tang 2022-07-01 15:47 ` Shakeel Butt 2022-07-01 15:47 ` Shakeel Butt 2022-07-03 10:43 ` Feng Tang 2022-07-03 10:43 ` Feng Tang 2022-07-03 22:55 ` Roman Gushchin 2022-07-03 22:55 ` Roman Gushchin 2022-07-05 5:03 ` Feng Tang 2022-07-05 5:03 ` Feng Tang 2022-08-16 5:52 ` Oliver Sang 2022-08-16 5:52 ` Oliver Sang 2022-08-16 15:55 ` Shakeel Butt 2022-08-16 15:55 ` Shakeel Butt 2022-06-27 14:52 ` Shakeel Butt 2022-06-27 14:52 ` Shakeel Butt 2022-06-27 14:56 ` Eric Dumazet 2022-06-27 14:56 ` Eric Dumazet 2022-06-27 15:12 ` Feng Tang 2022-06-27 15:12 ` Feng Tang 2022-06-27 16:25 ` Shakeel Butt 2022-06-27 16:25 ` Shakeel Butt
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