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

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Date:	Tue, 05 Mar 2013 23:14:32 -0800
From:	Davidlohr Bueso <davidlohr.bueso@...com>
To:	Rik van Riel <riel@...hat.com>
Cc:	Waiman Long <Waiman.Long@...com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	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, 2013-03-05 at 22:53 -0500, Rik van Riel wrote:
> 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.

Great, looking forward.

Thanks,
Davidlohr


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