From: kernel test robot <rong.a.chen@intel.com>
To: dsterba@suse.cz, Johannes Thumshirn <jthumshirn@suse.de>,
lkp@01.org, Linus Torvalds <torvalds@linux-foundation.org>,
Nikolay Borisov <nborisov@suse.com>, WenRuo Qu <wqu@suse.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [btrfs] 2996e1f8bc: aim7.jobs-per-min -13.2% regression
Date: Thu, 30 May 2019 21:32:15 +0800 [thread overview]
Message-ID: <20190530133215.GC22325@shao2-debian> (raw)
In-Reply-To: <20190527114914.GG15290@suse.cz>
On Mon, May 27, 2019 at 01:49:14PM +0200, David Sterba wrote:
> On Mon, May 27, 2019 at 05:17:19PM +0800, kernel test robot wrote:
> > Greeting,
> >
> > FYI, we noticed a -13.2% regression of aim7.jobs-per-min due to commit:
>
> That's interesting and worth an investigation. This should not happen,
> the code is almost the same, moved from one function to another and the
> call is direct. I'd suspect some low-level causes like cache effects or
> branching, the perf-stats.i.* show some differences.
>
> Other stats say (slabinfo.*extent_buffer) that there was less work over
> the period. The slab object counter says that the object reuse was
> higher in the bad case.
>
> And there are many stats that show two digit difference, I'm trying to
> make some sense of that, eg. if memory placement on NUMA nodes can
> affect the speed of checksumming (changed by the patch)
>
> So I wonder how reliable the test is and if it really does the same
> thing in both cases or if there's some subtle change in the patch that
> we've missed.
Hi,
The test is unstable, we can't reproduce the issue. It's probably a false
positive, 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: [btrfs] 2996e1f8bc: aim7.jobs-per-min -13.2% regression
Date: Thu, 30 May 2019 21:32:15 +0800 [thread overview]
Message-ID: <20190530133215.GC22325@shao2-debian> (raw)
In-Reply-To: <20190527114914.GG15290@suse.cz>
[-- Attachment #1: Type: text/plain, Size: 1216 bytes --]
On Mon, May 27, 2019 at 01:49:14PM +0200, David Sterba wrote:
> On Mon, May 27, 2019 at 05:17:19PM +0800, kernel test robot wrote:
> > Greeting,
> >
> > FYI, we noticed a -13.2% regression of aim7.jobs-per-min due to commit:
>
> That's interesting and worth an investigation. This should not happen,
> the code is almost the same, moved from one function to another and the
> call is direct. I'd suspect some low-level causes like cache effects or
> branching, the perf-stats.i.* show some differences.
>
> Other stats say (slabinfo.*extent_buffer) that there was less work over
> the period. The slab object counter says that the object reuse was
> higher in the bad case.
>
> And there are many stats that show two digit difference, I'm trying to
> make some sense of that, eg. if memory placement on NUMA nodes can
> affect the speed of checksumming (changed by the patch)
>
> So I wonder how reliable the test is and if it really does the same
> thing in both cases or if there's some subtle change in the patch that
> we've missed.
Hi,
The test is unstable, we can't reproduce the issue. It's probably a false
positive, sorry for the inconvenience.
Best Regards,
Rong Chen
next prev parent reply other threads:[~2019-05-30 13:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-27 9:17 [btrfs] 2996e1f8bc: aim7.jobs-per-min -13.2% regression kernel test robot
2019-05-27 9:17 ` kernel test robot
2019-05-27 11:49 ` David Sterba
2019-05-27 11:49 ` David Sterba
2019-05-30 13:32 ` kernel test robot [this message]
2019-05-30 13:32 ` kernel test robot
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