From: kernel test robot <rong.a.chen@intel.com>
To: Ian Kent <raven@themaw.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>, Tejun Heo <tj@kernel.org>,
Rick Lindsley <ricklind@linux.vnet.ibm.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
David Howells <dhowells@redhat.com>,
Miklos Szeredi <miklos@szeredi.hu>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Kernel Mailing List <linux-kernel@vger.kernel.org>,
lkp@lists.01.org
Subject: Re: [kernfs] ea7c5fc39a: stress-ng.stream.ops_per_sec 11827.2% improvement
Date: Thu, 11 Jun 2020 10:06:57 +0800 [thread overview]
Message-ID: <20200611020657.GI12456@shao2-debian> (raw)
In-Reply-To: <5df6bec6f1b332c993474782c08fe8db30bffddc.camel@themaw.net>
On Sun, Jun 07, 2020 at 09:13:08AM +0800, Ian Kent wrote:
> On Sat, 2020-06-06 at 20:18 +0200, Greg Kroah-Hartman wrote:
> > On Sat, Jun 06, 2020 at 11:52:16PM +0800, kernel test robot wrote:
> > > Greeting,
> > >
> > > FYI, we noticed a 11827.2% improvement of stress-
> > > ng.stream.ops_per_sec due to commit:
> > >
> > >
> > > commit: ea7c5fc39ab005b501e0c7666c29db36321e4f74 ("[PATCH 1/4]
> > > kernfs: switch kernfs to use an rwsem")
> > > url:
> > > https://github.com/0day-ci/linux/commits/Ian-Kent/kernfs-proposed-locking-and-concurrency-improvement/20200525-134849
> > >
> >
> > Seriously? That's a huge performance increase, and one that feels
> > really odd. Why would a stress-ng test be touching sysfs?
>
> That is unusually high even if there's a lot of sysfs or kernfs
> activity and that patch shouldn't improve VFS path walk contention
> very much even if it is present.
>
> Maybe I've missed something, and the information provided doesn't
> seem to be quite enough to even make a start on it.
>
> That's going to need some analysis which, for my part, will need to
> wait probably until around rc1 time frame to allow me to get through
> the push down stack (reactive, postponed due to other priorities) of
> jobs I have in order to get back to the fifo queue (longer term tasks,
> of which this is one) list of jobs I need to do as well, ;)
>
> Please, kernel test robot, more information about this test and what
> it's doing.
>
Hi Ian,
We increased the timeout of stress-ng from 1s to 32s, and there's only
3% improvement of stress-ng.stream.ops_per_sec:
fefcfc968723caf9 ea7c5fc39ab005b501e0c7666c testcase/testparams/testbox
---------------- -------------------------- ---------------------------
%stddev change %stddev
\ | \
10686 3% 11037 stress-ng/cpu-cache-performance-1HDD-100%-32s-ucode=0x500002c/lkp-csl-2sp5
10686 3% 11037 GEO-MEAN stress-ng.stream.ops_per_sec
It seems the result of stress-ng is inaccurate if test time too
short, we'll increase the test time to avoid unreasonable results,
sorry for the inconvenience.
Best Regards,
Rong Chen
WARNING: multiple messages have this Message-ID (diff)
From: kernel test robot <rong.a.chen@intel.com>
To: lkp@lists.01.org
Subject: Re: [kernfs] ea7c5fc39a: stress-ng.stream.ops_per_sec 11827.2% improvement
Date: Thu, 11 Jun 2020 10:06:57 +0800 [thread overview]
Message-ID: <20200611020657.GI12456@shao2-debian> (raw)
In-Reply-To: <5df6bec6f1b332c993474782c08fe8db30bffddc.camel@themaw.net>
[-- Attachment #1: Type: text/plain, Size: 2274 bytes --]
On Sun, Jun 07, 2020 at 09:13:08AM +0800, Ian Kent wrote:
> On Sat, 2020-06-06 at 20:18 +0200, Greg Kroah-Hartman wrote:
> > On Sat, Jun 06, 2020 at 11:52:16PM +0800, kernel test robot wrote:
> > > Greeting,
> > >
> > > FYI, we noticed a 11827.2% improvement of stress-
> > > ng.stream.ops_per_sec due to commit:
> > >
> > >
> > > commit: ea7c5fc39ab005b501e0c7666c29db36321e4f74 ("[PATCH 1/4]
> > > kernfs: switch kernfs to use an rwsem")
> > > url:
> > > https://github.com/0day-ci/linux/commits/Ian-Kent/kernfs-proposed-locking-and-concurrency-improvement/20200525-134849
> > >
> >
> > Seriously? That's a huge performance increase, and one that feels
> > really odd. Why would a stress-ng test be touching sysfs?
>
> That is unusually high even if there's a lot of sysfs or kernfs
> activity and that patch shouldn't improve VFS path walk contention
> very much even if it is present.
>
> Maybe I've missed something, and the information provided doesn't
> seem to be quite enough to even make a start on it.
>
> That's going to need some analysis which, for my part, will need to
> wait probably until around rc1 time frame to allow me to get through
> the push down stack (reactive, postponed due to other priorities) of
> jobs I have in order to get back to the fifo queue (longer term tasks,
> of which this is one) list of jobs I need to do as well, ;)
>
> Please, kernel test robot, more information about this test and what
> it's doing.
>
Hi Ian,
We increased the timeout of stress-ng from 1s to 32s, and there's only
3% improvement of stress-ng.stream.ops_per_sec:
fefcfc968723caf9 ea7c5fc39ab005b501e0c7666c testcase/testparams/testbox
---------------- -------------------------- ---------------------------
%stddev change %stddev
\ | \
10686 3% 11037 stress-ng/cpu-cache-performance-1HDD-100%-32s-ucode=0x500002c/lkp-csl-2sp5
10686 3% 11037 GEO-MEAN stress-ng.stream.ops_per_sec
It seems the result of stress-ng is inaccurate if test time too
short, we'll increase the test time to avoid unreasonable results,
sorry for the inconvenience.
Best Regards,
Rong Chen
next prev parent reply other threads:[~2020-06-11 2:07 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 5:46 [PATCH 0/4] kernfs: proposed locking and concurrency improvement Ian Kent
2020-05-25 5:47 ` [PATCH 1/4] kernfs: switch kernfs to use an rwsem Ian Kent
2020-06-06 15:52 ` [kernfs] ea7c5fc39a: stress-ng.stream.ops_per_sec 11827.2% improvement kernel test robot
2020-06-06 15:52 ` kernel test robot
2020-06-06 18:18 ` Greg Kroah-Hartman
2020-06-06 18:18 ` Greg Kroah-Hartman
2020-06-07 1:13 ` Ian Kent
2020-06-11 2:06 ` kernel test robot [this message]
2020-06-11 2:06 ` kernel test robot
2020-06-11 2:20 ` Rick Lindsley
2020-06-11 2:20 ` Rick Lindsley
2020-06-11 3:02 ` Ian Kent
2020-06-11 3:02 ` Ian Kent
2020-06-07 8:40 ` [PATCH 1/4] kernfs: switch kernfs to use an rwsem Ian Kent
2020-06-08 9:58 ` Ian Kent
2020-05-25 5:47 ` [PATCH 2/4] kernfs: move revalidate to be near lookup Ian Kent
2020-05-25 5:47 ` [PATCH 3/4] kernfs: improve kernfs path resolution Ian Kent
2020-05-25 5:47 ` [PATCH 4/4] kernfs: use revision to identify directory node changes Ian Kent
2020-05-25 6:16 ` [PATCH 0/4] kernfs: proposed locking and concurrency improvement Greg Kroah-Hartman
2020-05-25 7:23 ` Ian Kent
2020-05-25 7:31 ` Greg Kroah-Hartman
2020-05-27 12:44 ` Rick Lindsley
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