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From: Michal Hocko <mhocko@kernel.org>
To: "Lu, Aaron" <aaron.lu@intel.com>
Cc: "Ye, Xiaolong" <xiaolong.ye@intel.com>,
	"tj@kernel.org" <tj@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"lkp@01.org" <lkp@01.org>,
	"hannes@cmpxchg.org" <hannes@cmpxchg.org>
Subject: Re: [LKP] [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
Date: Tue, 29 May 2018 09:58:00 +0200	[thread overview]
Message-ID: <20180529075800.GL27180@dhcp22.suse.cz> (raw)
In-Reply-To: <dbd727326f53648ed114e03a85085b6b4655fda2.camel@intel.com>

On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > 
> > > Greeting,
> > > 
> > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to commit:
> > > 
> > > 
> > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol: implement memory.swap.events")
> > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> > 
> > This doesn't make any sense to me. The patch merely adds an accounting.
> > It doesn't optimize anything. So I strongly suspect the result is just
> > misleading or the test (environment) misconfigured. Not the first time
> > I am seeing something like that I am afraid.
> > 
> 
> Most likely the same situation as:
> "
> FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> due to commit:
> 
> 
> commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> memory.events is uptodate when waking pollers")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> "
> 
> Where the performance change is due to layout change of
> 'struct mem_cgroup':
> http://lkml.kernel.org/r/20180528085201.GA2918@intel.com

I do not follow. How can _this_ patch lead to an improvement when it
actually _adds_ an accounting? The other report you are mentioning is a
_regression_ and I can imagine that the layout changes can lead to that
result.
-- 
Michal Hocko
SUSE Labs

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: lkp@lists.01.org
Subject: Re: [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement
Date: Tue, 29 May 2018 09:58:00 +0200	[thread overview]
Message-ID: <20180529075800.GL27180@dhcp22.suse.cz> (raw)
In-Reply-To: <dbd727326f53648ed114e03a85085b6b4655fda2.camel@intel.com>

[-- Attachment #1: Type: text/plain, Size: 1526 bytes --]

On Tue 29-05-18 03:15:51, Lu, Aaron wrote:
> On Mon, 2018-05-28 at 14:03 +0200, Michal Hocko wrote:
> > On Mon 28-05-18 19:40:19, kernel test robot wrote:
> > > 
> > > Greeting,
> > > 
> > > FYI, we noticed a +23.0% improvement of vm-scalability.throughput due to commit:
> > > 
> > > 
> > > commit: 309fe96bfc0ae387f53612927a8f0dc3eb056efd ("mm, memcontrol: implement memory.swap.events")
> > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> > 
> > This doesn't make any sense to me. The patch merely adds an accounting.
> > It doesn't optimize anything. So I strongly suspect the result is just
> > misleading or the test (environment) misconfigured. Not the first time
> > I am seeing something like that I am afraid.
> > 
> 
> Most likely the same situation as:
> "
> FYI, we noticed a -27.2% regression of will-it-scale.per_process_ops
> due to commit:
> 
> 
> commit: e27be240df53f1a20c659168e722b5d9f16cc7f4 ("mm: memcg: make sure
> memory.events is uptodate when waking pollers")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> "
> 
> Where the performance change is due to layout change of
> 'struct mem_cgroup':
> http://lkml.kernel.org/r/20180528085201.GA2918(a)intel.com

I do not follow. How can _this_ patch lead to an improvement when it
actually _adds_ an accounting? The other report you are mentioning is a
_regression_ and I can imagine that the layout changes can lead to that
result.
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-05-29  7:58 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-28 11:40 [lkp-robot] [mm, memcontrol] 309fe96bfc: vm-scalability.throughput +23.0% improvement kernel test robot
2018-05-28 11:40 ` kernel test robot
2018-05-28 12:03 ` Michal Hocko
2018-05-28 12:03   ` Michal Hocko
2018-05-29  3:15   ` [LKP] " Lu, Aaron
2018-05-29  3:15     ` Lu, Aaron
2018-05-29  7:58     ` Michal Hocko [this message]
2018-05-29  7:58       ` Michal Hocko
2018-05-29  8:11       ` [LKP] " Aaron Lu
2018-05-29  8:11         ` Aaron Lu
2018-05-29  8:27         ` [LKP] " Michal Hocko
2018-05-29  8:27           ` Michal Hocko
2018-05-29  9:00           ` [LKP] " Aaron Lu
2018-05-29  9:00             ` Aaron Lu
2018-06-01  7:26 ` [LKP] " Aaron Lu
2018-06-01  7:26   ` Aaron Lu
2018-06-06  8:50   ` [LKP] " Aaron Lu
2018-06-06  8:50     ` Aaron Lu

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