From mboxrd@z Thu Jan 1 00:00:00 1970 From: Feng Tang Subject: Re: [PATCH 2/3] mm: page_counter: rearrange struct page_counter fields Date: Mon, 22 Aug 2022 10:10:58 +0800 Message-ID: References: <20220822001737.4120417-1-shakeelb@google.com> <20220822001737.4120417-3-shakeelb@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661134315; x=1692670315; h=date:from:to:cc:subject:message-id:references: in-reply-to:mime-version; bh=78YdFVWcZoZhkv1NVUGW31kEaECXwO+E+G/qPSQW6CE=; b=W/ogPRAHKvkWGHaeJwu1BdfXzzN6zIwdZhVnUKZIcnbt/bGoxbkoQmMK njXbpjpNyLm5kft8G+fzU7QYgiOD06CrU39FXr83dPHaOg3TnwZnP3AzG XTqXCmNcxLSFv8cbO36Z8hXreQP+rnwowWLu1wZsORHc0VBUNIwpFeeLd VysuSoR1jePUJwzBIFtQHxGKOmlerbJad+kquCRkInfJJC8HtEuW1Qzih rgqhCYgPzpvl4iirFbX7WCKqunPYADA+Xruj+Gt5GL2zGhKoUXRVdqCX4 O7XhunBnPb1gOnXnuoiNzgggJfDi1NqHlU3iJJ/3Dl/vyN6j7ZtBjdiE+ g==; Content-Disposition: inline In-Reply-To: <20220822001737.4120417-3-shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> List-ID: Content-Transfer-Encoding: 7bit To: Shakeel Butt Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Michal Koutn?? , Eric Dumazet , Soheil Hassas Yeganeh , "Sang, Oliver" , Andrew Morton , "lkp-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org" , "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org" , "netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" On Mon, Aug 22, 2022 at 08:17:36AM +0800, Shakeel Butt 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 with top > level having min and low setup appropriately. More specifically > memory.min equal to size of netperf binary and memory.low double of > that. > > $ 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. 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. > > Signed-off-by: Shakeel Butt > Reported-by: kernel test robot Looks good to me, with one nit below. Reviewed-by: Feng Tang > --- > include/linux/page_counter.h | 34 +++++++++++++++++++++++----------- > 1 file changed, 23 insertions(+), 11 deletions(-) > > diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h > index 679591301994..8ce99bde645f 100644 > --- a/include/linux/page_counter.h > +++ b/include/linux/page_counter.h > @@ -3,15 +3,27 @@ > #define _LINUX_PAGE_COUNTER_H > > #include > +#include > #include > #include > > +#if defined(CONFIG_SMP) > +struct pc_padding { > + char x[0]; > +} ____cacheline_internodealigned_in_smp; > +#define PC_PADDING(name) struct pc_padding name > +#else > +#define PC_PADDING(name) > +#endif There are 2 similar padding definitions in mmzone.h and memcontrol.h: struct memcg_padding { char x[0]; } ____cacheline_internodealigned_in_smp; #define MEMCG_PADDING(name) struct memcg_padding name struct zone_padding { char x[0]; } ____cacheline_internodealigned_in_smp; #define ZONE_PADDING(name) struct zone_padding name; Maybe we can generalize them, and lift it into include/cache.h? so that more places can reuse it in future. Thanks, Feng