linux-kernel - Re: [PATCH v2 0/4] ipc: reduce ipc lock contention

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Message-ID: <CA+55aFw7j1qLeNxhjfDqc1_MVHkr0m=VPGE+Lx5AmCBwxf8xyQ@mail.gmail.com>
Date:	Wed, 6 Mar 2013 08:01:39 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Davidlohr Bueso <davidlohr.bueso@...com>
Cc:	Rik van Riel <riel@...hat.com>,
	Emmanuel Benisty <benisty.e@...il.com>,
	"Vinod, Chegu" <chegu_vinod@...com>,
	"Low, Jason" <jason.low2@...com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>, aquini@...hat.com,
	Michel Lespinasse <walken@...gle.com>,
	Ingo Molnar <mingo@...nel.org>,
	Larry Woodman <lwoodman@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2 0/4] ipc: reduce ipc lock contention

On Tue, Mar 5, 2013 at 11:13 PM, Davidlohr Bueso <davidlohr.bueso@...com> wrote:
>
> Digging into the _raw_spin_lock call:
>
>  17.86%           oracle  [kernel.kallsyms]   [k] _raw_spin_lock
>                      |
>                      --- _raw_spin_lock
>                         |
>                         |--49.55%-- sys_semtimedop
>                         |          |
>                         |          |--77.41%-- system_call
>                         |          |          semtimedop
>                         |          |          skgpwwait
>                         |          |          ksliwat
>                         |          |          kslwaitctx

Hmm. It looks like you cut that off a bit too early. This shows that
half the cases came from sys_semtimedop. Where did the other half come
from?

             Linus
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