From: Borislav Petkov <bp@alien8.de>
To: Wedson Almeida Filho <wedsonaf@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64
Date: Mon, 1 Jul 2013 00:00:04 +0200 [thread overview]
Message-ID: <20130630220004.GA23124@pd.tnic> (raw)
In-Reply-To: <CANeycqpiXO-B1+f-OXZfHaxxPd2aVEL0kutFp6-sALHqXNrazQ@mail.gmail.com>
On Sat, Jun 29, 2013 at 04:56:30PM -0700, Wedson Almeida Filho wrote:
> On Fri, Jun 28, 2013 at 7:09 AM, Borislav Petkov <bp@alien8.de> wrote:
>
> > Btw, do we have any perf data showing any improvements from this patch?
>
> I wrote a simple test the measures the time it takes to acquire and
> release an uncontended mutex (i.e., we always take the fast path)
> 100k times. I ran it a few times, the original code averages
> 2.743436ms, and the new code averages 2.101098ms, so it's about 23% improvement.
Microbenchmark results tend to be misleading in such situations. Rather,
it would be much closer to reality if you traced a real workload like a
simple kernel build, for example, with and without your patch.
I.e., something like
perf stat --repeat 5 ./build-kernel.sh
and take a look at what the perfcouters are saying in both cases.
> I also think the code looks cleaner this way.
No doubt.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2013-06-30 22:00 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-28 10:54 [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64 Wedson Almeida Filho
2013-06-28 11:19 ` Ingo Molnar
2013-06-28 14:09 ` Borislav Petkov
2013-06-28 14:12 ` H. Peter Anvin
2013-06-28 15:15 ` Peter Zijlstra
2013-06-28 16:41 ` [PATCH] x86, cpufeature: Use new CC_HAVE_ASM_GOTO Borislav Petkov
2013-07-05 14:24 ` [tip:x86/cpu] " tip-bot for Borislav Petkov
2013-06-29 23:56 ` [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64 Wedson Almeida Filho
2013-06-30 22:00 ` Borislav Petkov [this message]
2013-07-01 7:50 ` Ingo Molnar
2013-07-01 10:23 ` Borislav Petkov
2013-07-01 11:11 ` Ingo Molnar
2013-07-01 12:29 ` Borislav Petkov
2013-07-01 12:50 ` Ingo Molnar
2013-07-01 14:48 ` Borislav Petkov
2013-07-01 22:28 ` Borislav Petkov
2013-07-01 22:35 ` Wedson Almeida Filho
2013-07-01 22:44 ` Borislav Petkov
2013-07-02 6:39 ` Ingo Molnar
2013-07-02 10:29 ` Borislav Petkov
2013-07-01 14:30 ` H. Peter Anvin
2013-07-01 14:36 ` Borislav Petkov
2013-07-01 14:45 ` H. Peter Anvin
2013-07-01 14:50 ` Borislav Petkov
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