From: Dan Williams <dan.j.williams@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: kernel test robot <rong.a.chen@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
stable <stable@vger.kernel.org>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tony Luck <tony.luck@intel.com>,
Erwin Tsaur <erwin.tsaur@intel.com>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
0day robot <lkp@intel.com>,
lkp@lists.01.org
Subject: Re: [x86/copy_mc] a0ac629ebe: fio.read_iops -43.3% regression
Date: Thu, 6 Aug 2020 08:19:52 -0700 [thread overview]
Message-ID: <CAPcyv4hS7K0Arrd+C0LhjrFH=yGJf3g55_WkHOET4z58AcWrJw@mail.gmail.com> (raw)
In-Reply-To: <20200806133452.GA2077191@gmail.com>
On Thu, Aug 6, 2020 at 6:35 AM Ingo Molnar <mingo@kernel.org> wrote:
>
>
> * kernel test robot <rong.a.chen@intel.com> wrote:
>
> > Greeting,
> >
> > FYI, we noticed a -43.3% regression of fio.read_iops due to commit:
> >
> >
> > commit: a0ac629ebe7b3d248cb93807782a00d9142fdb98 ("x86/copy_mc: Introduce copy_mc_generic()")
> > url: https://github.com/0day-ci/linux/commits/Dan-Williams/Renovate-memcpy_mcsafe-with-copy_mc_to_-user-kernel/20200802-014046
> >
> >
> > in testcase: fio-basic
> > on test machine: 96 threads Intel(R) Xeon(R) Gold 6252 CPU @ 2.10GHz with 256G memory
> > with following parameters:
>
> So this performance regression, if it isn't a spurious result, looks
> concerning. Is this expected?
This is not expected and I think delays these patches until I'm back
from leave in a few weeks. I know that we might lose some inlining
effect due to replacing native memcpy, but I did not expect it would
have an impact like this. In my testing I was seeing a performance
improvement from replacing the careful / open-coded copy with rep;
mov;, which increases the surprise of this result.
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WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: kernel test robot <rong.a.chen@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Vishal L Verma <vishal.l.verma@intel.com>,
X86 ML <x86@kernel.org>, stable <stable@vger.kernel.org>,
Borislav Petkov <bp@alien8.de>, Vivek Goyal <vgoyal@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tony Luck <tony.luck@intel.com>,
Erwin Tsaur <erwin.tsaur@intel.com>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
0day robot <lkp@intel.com>,
lkp@lists.01.org
Subject: Re: [x86/copy_mc] a0ac629ebe: fio.read_iops -43.3% regression
Date: Thu, 6 Aug 2020 08:19:52 -0700 [thread overview]
Message-ID: <CAPcyv4hS7K0Arrd+C0LhjrFH=yGJf3g55_WkHOET4z58AcWrJw@mail.gmail.com> (raw)
In-Reply-To: <20200806133452.GA2077191@gmail.com>
On Thu, Aug 6, 2020 at 6:35 AM Ingo Molnar <mingo@kernel.org> wrote:
>
>
> * kernel test robot <rong.a.chen@intel.com> wrote:
>
> > Greeting,
> >
> > FYI, we noticed a -43.3% regression of fio.read_iops due to commit:
> >
> >
> > commit: a0ac629ebe7b3d248cb93807782a00d9142fdb98 ("x86/copy_mc: Introduce copy_mc_generic()")
> > url: https://github.com/0day-ci/linux/commits/Dan-Williams/Renovate-memcpy_mcsafe-with-copy_mc_to_-user-kernel/20200802-014046
> >
> >
> > in testcase: fio-basic
> > on test machine: 96 threads Intel(R) Xeon(R) Gold 6252 CPU @ 2.10GHz with 256G memory
> > with following parameters:
>
> So this performance regression, if it isn't a spurious result, looks
> concerning. Is this expected?
This is not expected and I think delays these patches until I'm back
from leave in a few weeks. I know that we might lose some inlining
effect due to replacing native memcpy, but I did not expect it would
have an impact like this. In my testing I was seeing a performance
improvement from replacing the careful / open-coded copy with rep;
mov;, which increases the surprise of this result.
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: lkp@lists.01.org
Subject: Re: [x86/copy_mc] a0ac629ebe: fio.read_iops -43.3% regression
Date: Thu, 06 Aug 2020 08:19:52 -0700 [thread overview]
Message-ID: <CAPcyv4hS7K0Arrd+C0LhjrFH=yGJf3g55_WkHOET4z58AcWrJw@mail.gmail.com> (raw)
In-Reply-To: <20200806133452.GA2077191@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1132 bytes --]
On Thu, Aug 6, 2020 at 6:35 AM Ingo Molnar <mingo@kernel.org> wrote:
>
>
> * kernel test robot <rong.a.chen@intel.com> wrote:
>
> > Greeting,
> >
> > FYI, we noticed a -43.3% regression of fio.read_iops due to commit:
> >
> >
> > commit: a0ac629ebe7b3d248cb93807782a00d9142fdb98 ("x86/copy_mc: Introduce copy_mc_generic()")
> > url: https://github.com/0day-ci/linux/commits/Dan-Williams/Renovate-memcpy_mcsafe-with-copy_mc_to_-user-kernel/20200802-014046
> >
> >
> > in testcase: fio-basic
> > on test machine: 96 threads Intel(R) Xeon(R) Gold 6252 CPU @ 2.10GHz with 256G memory
> > with following parameters:
>
> So this performance regression, if it isn't a spurious result, looks
> concerning. Is this expected?
This is not expected and I think delays these patches until I'm back
from leave in a few weeks. I know that we might lose some inlining
effect due to replacing native memcpy, but I did not expect it would
have an impact like this. In my testing I was seeing a performance
improvement from replacing the careful / open-coded copy with rep;
mov;, which increases the surprise of this result.
next prev parent reply other threads:[~2020-08-06 15:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-01 17:22 [PATCH v8 0/2] Renovate memcpy_mcsafe with copy_mc_to_{user, kernel} Dan Williams
2020-08-01 17:22 ` Dan Williams
2020-08-01 17:22 ` [PATCH v8 1/2] x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() Dan Williams
2020-08-01 17:22 ` Dan Williams
2020-08-06 1:24 ` Sasha Levin
2020-08-09 15:53 ` Sasha Levin
2020-08-13 16:25 ` Sasha Levin
2020-08-01 17:22 ` [PATCH v8 2/2] x86/copy_mc: Introduce copy_mc_generic() Dan Williams
2020-08-01 17:22 ` Dan Williams
2020-08-03 9:42 ` [x86/copy_mc] a0ac629ebe: fio.read_iops -43.3% regression kernel test robot
2020-08-03 9:42 ` kernel test robot
2020-08-03 9:42 ` kernel test robot
2020-08-06 13:34 ` Ingo Molnar
2020-08-06 13:34 ` Ingo Molnar
2020-08-06 13:34 ` Ingo Molnar
2020-08-06 15:19 ` Dan Williams [this message]
2020-08-06 15:19 ` Dan Williams
2020-08-06 15:19 ` Dan Williams
2020-08-06 15:35 ` Ingo Molnar
2020-08-06 15:35 ` Ingo Molnar
2020-08-06 15:35 ` Ingo Molnar
2020-08-07 7:16 ` kernel test robot
2020-08-07 7:16 ` kernel test robot
2020-08-07 7:16 ` kernel test robot
2020-09-23 0:26 ` Dan Williams
2020-09-23 0:26 ` Dan Williams
2020-09-23 0:26 ` Dan Williams
2020-08-06 1:24 ` [PATCH v8 2/2] x86/copy_mc: Introduce copy_mc_generic() Sasha Levin
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