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

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Date:	Tue, 05 Mar 2013 22:53:37 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Waiman Long <Waiman.Long@...com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Davidlohr Bueso <davidlohr.bueso@...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 03/05/2013 10:46 PM, Waiman Long wrote:
> On 03/05/2013 03:53 PM, Rik van Riel wrote:

>> Indeed.  Though how well my patches will work with Oracle will
>> depend a lot on what kind of semctl syscalls they are doing.
>>
>> Does Oracle typically do one semop per semctl syscall, or does
>> it pass in a whole bunch at once?
>
> i had collected a strace log of Oracle instance startup a while ago. In
> the log, almost all of the semctl() call is to set a single semaphore
> value in one of the element of the array using SETVAL. Also there are
> far more semtimedop() than semctl(), about 100:1. Again, all the
> semtimedop() operations are on a single element of the semaphore array.

That is good to hear. Just what I was hoping when I started
working on my patches. You should expect them tomorrow or
Thursday.

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