From: Dave Chinner <dchinner@redhat.com>
To: lkp@lists.01.org
Subject: Re: [xfs] bad77c375e: stress-ng.fallocate.ops_per_sec -10.0% regression
Date: Fri, 03 Dec 2021 09:04:51 +1100 [thread overview]
Message-ID: <20211202220451.GT2206@rh> (raw)
In-Reply-To: <96fa41bb-7e9f-ae47-bf34-accef5c36fa8@linux.intel.com>
[-- Attachment #1: Type: text/plain, Size: 1201 bytes --]
On Tue, Nov 30, 2021 at 02:46:06PM +0800, Xing Zhengjun wrote:
> Hi Dave,
>
> Do you have time to look at this? It still existed in v5.16-rc3. Thanks
AFAIC, it's a "don't care" issue.
The series of commits around this one:
> > > FYI, we noticed a -10.0% regression of
> > > stress-ng.fallocate.ops_per_sec due to commit:
> > >
> > >
> > > commit: bad77c375e8de6c776c848e443f7dc2d0d909be5 ("xfs: CIL
> > > checkpoint flushes caches unconditionally")
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
changed how we manage FUA/cache flushes for the journal changed
performance across a wide range of workloads. Many went a lot
faster, some (like this one) went slightly slower. Overall it was a
net win, especially on storage stacks with really slow cache flushes
(e.g. dm-thinp) and workloads that do a lot of concurrent metadata
modification.
Overall, fallocate is not a performance critical path - it's a
slowpath because it serialises all IO to that file while the
fallocate call runs. Hence performance characteristics for fallocate
aren't really a major concern to begin with...
-Dave.
--
Dave Chinner
dchinner(a)redhat.com
WARNING: multiple messages have this Message-ID (diff)
From: Dave Chinner <dchinner@redhat.com>
To: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: kernel test robot <oliver.sang@intel.com>,
"Darrick J. Wong" <djwong@kernel.org>,
Chandan Babu R <chandanrlinux@gmail.com>,
Brian Foster <bfoster@redhat.com>,
Allison Henderson <allison.henderson@oracle.com>,
LKML <linux-kernel@vger.kernel.org>,
lkp@lists.01.org, lkp@intel.com
Subject: Re: [LKP] Re: [xfs] bad77c375e: stress-ng.fallocate.ops_per_sec -10.0% regression
Date: Fri, 3 Dec 2021 09:04:51 +1100 [thread overview]
Message-ID: <20211202220451.GT2206@rh> (raw)
In-Reply-To: <96fa41bb-7e9f-ae47-bf34-accef5c36fa8@linux.intel.com>
On Tue, Nov 30, 2021 at 02:46:06PM +0800, Xing Zhengjun wrote:
> Hi Dave,
>
> Do you have time to look at this? It still existed in v5.16-rc3. Thanks
AFAIC, it's a "don't care" issue.
The series of commits around this one:
> > > FYI, we noticed a -10.0% regression of
> > > stress-ng.fallocate.ops_per_sec due to commit:
> > >
> > >
> > > commit: bad77c375e8de6c776c848e443f7dc2d0d909be5 ("xfs: CIL
> > > checkpoint flushes caches unconditionally")
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
changed how we manage FUA/cache flushes for the journal changed
performance across a wide range of workloads. Many went a lot
faster, some (like this one) went slightly slower. Overall it was a
net win, especially on storage stacks with really slow cache flushes
(e.g. dm-thinp) and workloads that do a lot of concurrent metadata
modification.
Overall, fallocate is not a performance critical path - it's a
slowpath because it serialises all IO to that file while the
fallocate call runs. Hence performance characteristics for fallocate
aren't really a major concern to begin with...
-Dave.
--
Dave Chinner
dchinner@redhat.com
next prev parent reply other threads:[~2021-12-02 22:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 7:27 [xfs] bad77c375e: stress-ng.fallocate.ops_per_sec -10.0% regression kernel test robot
2021-09-02 7:27 ` kernel test robot
2021-09-03 7:40 ` Xing Zhengjun
2021-09-03 7:40 ` Xing Zhengjun
2021-11-30 6:46 ` Xing Zhengjun
2021-11-30 6:46 ` [LKP] " Xing Zhengjun
2021-12-02 22:04 ` Dave Chinner [this message]
2021-12-02 22:04 ` Dave Chinner
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