From: Luming Yu <luming.yu@gmail.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Jinhua Wu <wujinhua@linux.alibaba.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
zelin.deng@linux.alibaba.com, jiayu.ni@linux.alibaba.com,
Andi Kleen <ak@linux.intel.com>, Luming Yu <luming.yu@intel.com>,
fan.du@intel.com, artie.ding@linux.alibaba.com, "Luck,
Tony" <tony.luck@intel.com>, Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
pawan.kumar.gupta@linux.intel.com, "Yu,
Fenghua" <fenghua.yu@intel.com>, "H. Peter Anvin" <hpa@zytor.com>,
ricardo.neri-calderon@linux.intel.com,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] perf: optimize clear page in Intel specified model with movq instruction
Date: Thu, 9 Sep 2021 18:34:40 +0800 [thread overview]
Message-ID: <CAJRGBZyQuQohbf8v3H19zo1mpbvDXrbNVXCJAUpCEmHgmqTYpg@mail.gmail.com> (raw)
In-Reply-To: <YTnWXIB42sCLbM2k@zn.tnic>
On Thu, Sep 9, 2021 at 5:41 PM Borislav Petkov <bp@alien8.de> wrote:
>
> On Thu, Sep 09, 2021 at 04:45:51PM +0800, Jinhua Wu wrote:
> > Clear page is the most time-consuming procedure in page fault handling.
> > Kernel use fast-string instruction to clear page. We found that in specified
> > Intel model such as CPX and ICX, the movq instruction perform much better
> > than fast-string instruction when corresponding page is not in cache.
> > But when the page is in cache, fast string perform better. We show the test
> > result in the following:
>
> What you should do is show the extensive tests you've run with
> real-world benchmarks where you really can show 40% performance
> improvement.
>
> Also, the static branch "approach" you're using ain't gonna happen. If
> anything, another X86_FEATURE_* bit.
do you mean jump label would not be replaced to nop when its key is enabled?
so we could not use it in certain functions?
I don't understand exactly what "ain't gonna happen"
>
> Good luck.
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-09-09 10:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-09 8:45 [PATCH] perf: optimize clear page in Intel specified model with movq instruction Jinhua Wu
2021-09-09 9:39 ` Borislav Petkov
2021-09-09 10:34 ` Luming Yu [this message]
2021-09-09 10:44 ` Borislav Petkov
2021-09-09 11:18 ` Peter Zijlstra
[not found] ` <bf6fe59d-c760-40d4-8201-4170cd90ffc3.wujinhua@linux.alibaba.com>
2021-09-09 11:07 ` 回复：[PATCH] " Borislav Petkov
2021-09-09 14:51 ` Luming Yu
[not found] ` <1cac1499-6b00-3c18-b64c-a22f269a2706@linux.alibaba.com>
2021-10-16 13:22 ` Borislav Petkov
[not found] ` <7b07f141-12f5-397d-9e45-1d507cacae84@linux.alibaba.com>
2021-10-18 12:43 ` Borislav Petkov
2021-10-18 14:44 ` Luming Yu
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