From: Michal Hocko <mhocko@kernel.org>
To: Aaron Lu <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 10:27:51 +0200 [thread overview]
Message-ID: <20180529082751.GQ27180@dhcp22.suse.cz> (raw)
In-Reply-To: <20180529081127.GB14785@intel.com>
On Tue 29-05-18 16:11:27, Aaron Lu wrote:
> On Tue, May 29, 2018 at 09:58:00AM +0200, Michal Hocko wrote:
> > 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
>
> This patch also changed the layout of 'struct mem_cgroup':
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d99b71bc2c66..517096c3cc99 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -208,6 +210,9 @@ struct mem_cgroup {
> atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
> struct cgroup_file events_file;
>
> + /* handle for "memory.swap.events" */
> + struct cgroup_file swap_events_file;
> +
> /* protect arrays of thresholds */
> struct mutex thresholds_lock;
>
> And I'm guessing that might be the cause.
Ohh, you are right! Sorry, I've missed that part.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-05-29 8:27 UTC|newest]
Thread overview: 9+ 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 12:03 ` Michal Hocko
2018-05-29 3:15 ` [LKP] " Lu, Aaron
2018-05-29 7:58 ` Michal Hocko
2018-05-29 8:11 ` Aaron Lu
2018-05-29 8:27 ` Michal Hocko [this message]
2018-05-29 9:00 ` Aaron Lu
2018-06-01 7:26 ` Aaron Lu
2018-06-06 8:50 ` Aaron Lu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180529082751.GQ27180@dhcp22.suse.cz \
--to=mhocko@kernel.org \
--cc=aaron.lu@intel.com \
--cc=hannes@cmpxchg.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@01.org \
--cc=tj@kernel.org \
--cc=xiaolong.ye@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).