From: Mel Gorman <mgorman-l3A5Bk7waGM@public.gmane.org>
To: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Cc: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Linux-CGroups <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Linux-MM <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH 2/2] mm, memcg: Optionally disable memcg by default using Kconfig
Date: Wed, 20 May 2015 17:44:19 +0100 [thread overview]
Message-ID: <20150520164419.GT2462@suse.de> (raw)
In-Reply-To: <20150520162421.GB2874-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
On Wed, May 20, 2015 at 12:24:21PM -0400, Johannes Weiner wrote:
> >
> > Low thread counts get a small boost but it's within noise as memcg overhead
> > does not dominate. It's not obvious at all at higher thread counts as other
> > factors cause more problems. The overall breakdown of CPU usage looks like
> >
> > 4.0.0 4.0.0
> > chargefirst-v2r1disable-v2r1
> > User 41.81 41.45
> > System 407.64 405.50
> > Elapsed 128.17 127.06
>
> This is a worst case microbenchmark doing nothing but anonymous page
> faults (with THP disabled), and yet the performance difference is in
> the noise. I don't see why we should burden the user with making a
> decision that doesn't matter in theory, let alone in practice.
>
> We have CONFIG_MEMCG and cgroup_disable=memory, that should be plenty
> for users that obsess about fluctuation in the noise. There is no
> reason to complicate the world further for everybody else.
FWIW, I agree and only included this patch because I said I would
yesterday. After patch 1, there is almost no motivation to disable memcg
at all let alone by default.
--
Mel Gorman
SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>,
Linux-CGroups <cgroups@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm, memcg: Optionally disable memcg by default using Kconfig
Date: Wed, 20 May 2015 17:44:19 +0100 [thread overview]
Message-ID: <20150520164419.GT2462@suse.de> (raw)
In-Reply-To: <20150520162421.GB2874@cmpxchg.org>
On Wed, May 20, 2015 at 12:24:21PM -0400, Johannes Weiner wrote:
> >
> > Low thread counts get a small boost but it's within noise as memcg overhead
> > does not dominate. It's not obvious at all at higher thread counts as other
> > factors cause more problems. The overall breakdown of CPU usage looks like
> >
> > 4.0.0 4.0.0
> > chargefirst-v2r1disable-v2r1
> > User 41.81 41.45
> > System 407.64 405.50
> > Elapsed 128.17 127.06
>
> This is a worst case microbenchmark doing nothing but anonymous page
> faults (with THP disabled), and yet the performance difference is in
> the noise. I don't see why we should burden the user with making a
> decision that doesn't matter in theory, let alone in practice.
>
> We have CONFIG_MEMCG and cgroup_disable=memory, that should be plenty
> for users that obsess about fluctuation in the noise. There is no
> reason to complicate the world further for everybody else.
FWIW, I agree and only included this patch because I said I would
yesterday. After patch 1, there is almost no motivation to disable memcg
at all let alone by default.
--
Mel Gorman
SUSE Labs
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WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>,
Linux-CGroups <cgroups@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] mm, memcg: Optionally disable memcg by default using Kconfig
Date: Wed, 20 May 2015 17:44:19 +0100 [thread overview]
Message-ID: <20150520164419.GT2462@suse.de> (raw)
In-Reply-To: <20150520162421.GB2874@cmpxchg.org>
On Wed, May 20, 2015 at 12:24:21PM -0400, Johannes Weiner wrote:
> >
> > Low thread counts get a small boost but it's within noise as memcg overhead
> > does not dominate. It's not obvious at all at higher thread counts as other
> > factors cause more problems. The overall breakdown of CPU usage looks like
> >
> > 4.0.0 4.0.0
> > chargefirst-v2r1disable-v2r1
> > User 41.81 41.45
> > System 407.64 405.50
> > Elapsed 128.17 127.06
>
> This is a worst case microbenchmark doing nothing but anonymous page
> faults (with THP disabled), and yet the performance difference is in
> the noise. I don't see why we should burden the user with making a
> decision that doesn't matter in theory, let alone in practice.
>
> We have CONFIG_MEMCG and cgroup_disable=memory, that should be plenty
> for users that obsess about fluctuation in the noise. There is no
> reason to complicate the world further for everybody else.
FWIW, I agree and only included this patch because I said I would
yesterday. After patch 1, there is almost no motivation to disable memcg
at all let alone by default.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2015-05-20 16:44 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-20 12:50 [PATCH 0/2] Reduce overhead of memcg when unused Mel Gorman
2015-05-20 12:50 ` Mel Gorman
2015-05-20 12:50 ` Mel Gorman
2015-05-20 12:50 ` [PATCH 1/2] mm, memcg: Try charging a page before setting page up to date Mel Gorman
2015-05-20 12:50 ` Mel Gorman
2015-05-20 14:03 ` Michal Hocko
2015-05-20 14:03 ` Michal Hocko
[not found] ` <20150520140353.GC28678-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2015-05-20 14:18 ` Michal Hocko
2015-05-20 14:18 ` Michal Hocko
2015-05-20 14:18 ` Michal Hocko
2015-05-20 15:29 ` Johannes Weiner
2015-05-20 15:29 ` Johannes Weiner
[not found] ` <20150520152923.GA2874-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2015-05-20 16:15 ` Mel Gorman
2015-05-20 16:15 ` Mel Gorman
2015-05-20 16:15 ` Mel Gorman
2015-05-20 12:50 ` [PATCH 2/2] mm, memcg: Optionally disable memcg by default using Kconfig Mel Gorman
2015-05-20 12:50 ` Mel Gorman
2015-05-20 13:47 ` Davidlohr Bueso
2015-05-20 13:47 ` Davidlohr Bueso
2015-05-20 14:12 ` Michal Hocko
2015-05-20 14:12 ` Michal Hocko
2015-05-20 14:13 ` Mel Gorman
2015-05-20 14:13 ` Mel Gorman
[not found] ` <1432126245-10908-3-git-send-email-mgorman-l3A5Bk7waGM@public.gmane.org>
2015-05-20 16:24 ` Johannes Weiner
2015-05-20 16:24 ` Johannes Weiner
2015-05-20 16:24 ` Johannes Weiner
[not found] ` <20150520162421.GB2874-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
2015-05-20 16:44 ` Mel Gorman [this message]
2015-05-20 16:44 ` Mel Gorman
2015-05-20 16:44 ` Mel Gorman
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