From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755717AbeASNfS (ORCPT ); Fri, 19 Jan 2018 08:35:18 -0500 Received: from mx2.suse.de ([195.135.220.15]:34963 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754542AbeASNfM (ORCPT ); Fri, 19 Jan 2018 08:35:12 -0500 Date: Fri, 19 Jan 2018 14:35:10 +0100 From: Michal Hocko To: Andrey Ryabinin Cc: Andrew Morton , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Johannes Weiner , Vladimir Davydov Subject: Re: [PATCH v5 2/2] mm/memcontrol.c: Reduce reclaim retries in mem_cgroup_resize_limit() Message-ID: <20180119133510.GD6584@dhcp22.suse.cz> References: <20171220102429.31601-1-aryabinin@virtuozzo.com> <20180119132544.19569-1-aryabinin@virtuozzo.com> <20180119132544.19569-2-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180119132544.19569-2-aryabinin@virtuozzo.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 19-01-18 16:25:44, Andrey Ryabinin wrote: > Currently mem_cgroup_resize_limit() retries to set limit after reclaiming > 32 pages. It makes more sense to reclaim needed amount of pages right away. > > This works noticeably faster, especially if 'usage - limit' big. > E.g. bringing down limit from 4G to 50M: > > Before: > # perf stat echo 50M > memory.limit_in_bytes > > Performance counter stats for 'echo 50M': > > 386.582382 task-clock (msec) # 0.835 CPUs utilized > 2,502 context-switches # 0.006 M/sec > > 0.463244382 seconds time elapsed > > After: > # perf stat echo 50M > memory.limit_in_bytes > > Performance counter stats for 'echo 50M': > > 169.403906 task-clock (msec) # 0.849 CPUs utilized > 14 context-switches # 0.083 K/sec > > 0.199536900 seconds time elapsed But I am not going ack this one. As already stated this has a risk of over-reclaim if there a lot of charges are freed along with this shrinking. This is more of a theoretical concern so I am _not_ going to nack. If we ever see such a problem then reverting this patch should be pretty straghtforward. > Signed-off-by: Andrey Ryabinin > Cc: Shakeel Butt > Cc: Michal Hocko > Cc: Johannes Weiner > Cc: Vladimir Davydov > --- > mm/memcontrol.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 9d987f3e79dc..09bac2df2f12 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2448,6 +2448,7 @@ static DEFINE_MUTEX(memcg_limit_mutex); > static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, > unsigned long limit, bool memsw) > { > + unsigned long nr_pages; > bool enlarge = false; > int ret; > bool limits_invariant; > @@ -2479,8 +2480,9 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, > if (!ret) > break; > > - if (!try_to_free_mem_cgroup_pages(memcg, 1, > - GFP_KERNEL, !memsw)) { > + nr_pages = max_t(long, 1, page_counter_read(counter) - limit); > + if (!try_to_free_mem_cgroup_pages(memcg, nr_pages, > + GFP_KERNEL, !memsw)) { > ret = -EBUSY; > break; > } > -- > 2.13.6 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [PATCH v5 2/2] mm/memcontrol.c: Reduce reclaim retries in mem_cgroup_resize_limit() Date: Fri, 19 Jan 2018 14:35:10 +0100 Message-ID: <20180119133510.GD6584@dhcp22.suse.cz> References: <20171220102429.31601-1-aryabinin@virtuozzo.com> <20180119132544.19569-1-aryabinin@virtuozzo.com> <20180119132544.19569-2-aryabinin@virtuozzo.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20180119132544.19569-2-aryabinin@virtuozzo.com> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrey Ryabinin Cc: Andrew Morton , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Johannes Weiner , Vladimir Davydov On Fri 19-01-18 16:25:44, Andrey Ryabinin wrote: > Currently mem_cgroup_resize_limit() retries to set limit after reclaiming > 32 pages. It makes more sense to reclaim needed amount of pages right away. > > This works noticeably faster, especially if 'usage - limit' big. > E.g. bringing down limit from 4G to 50M: > > Before: > # perf stat echo 50M > memory.limit_in_bytes > > Performance counter stats for 'echo 50M': > > 386.582382 task-clock (msec) # 0.835 CPUs utilized > 2,502 context-switches # 0.006 M/sec > > 0.463244382 seconds time elapsed > > After: > # perf stat echo 50M > memory.limit_in_bytes > > Performance counter stats for 'echo 50M': > > 169.403906 task-clock (msec) # 0.849 CPUs utilized > 14 context-switches # 0.083 K/sec > > 0.199536900 seconds time elapsed But I am not going ack this one. As already stated this has a risk of over-reclaim if there a lot of charges are freed along with this shrinking. This is more of a theoretical concern so I am _not_ going to nack. If we ever see such a problem then reverting this patch should be pretty straghtforward. > Signed-off-by: Andrey Ryabinin > Cc: Shakeel Butt > Cc: Michal Hocko > Cc: Johannes Weiner > Cc: Vladimir Davydov > --- > mm/memcontrol.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 9d987f3e79dc..09bac2df2f12 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2448,6 +2448,7 @@ static DEFINE_MUTEX(memcg_limit_mutex); > static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, > unsigned long limit, bool memsw) > { > + unsigned long nr_pages; > bool enlarge = false; > int ret; > bool limits_invariant; > @@ -2479,8 +2480,9 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, > if (!ret) > break; > > - if (!try_to_free_mem_cgroup_pages(memcg, 1, > - GFP_KERNEL, !memsw)) { > + nr_pages = max_t(long, 1, page_counter_read(counter) - limit); > + if (!try_to_free_mem_cgroup_pages(memcg, nr_pages, > + GFP_KERNEL, !memsw)) { > ret = -EBUSY; > break; > } > -- > 2.13.6 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org