linux-kernel - Re: ipc,sem: sysv semaphore scalability

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Date:	Thu, 21 Mar 2013 23:40:09 -0400
From:	Rik van Riel <riel@...riel.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Davidlohr Bueso <davidlohr.bueso@...com>,
	Andrew Morton <akpm@...ux-foundation.org>, hhuang@...hat.com,
	"Low, Jason" <jason.low2@...com>,
	Michel Lespinasse <walken@...gle.com>,
	Larry Woodman <lwoodman@...hat.com>,
	"Vinod, Chegu" <chegu_vinod@...com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: ipc,sem: sysv semaphore scalability

On 03/21/2013 09:23 PM, Linus Torvalds wrote:
> On Thu, Mar 21, 2013 at 6:12 PM, Davidlohr Bueso <davidlohr.bueso@...com> wrote:
>>
>> ipc lock contention:
>> 100 users:  8,74%  (vanilla)    3.17% (v3 patchset)
>> 400 users:  21,86% (vanilla)    5.23% (v3 patchset)
>> 800 users   84,35% (vanilla)    7.39% (v3 patchset)
>
> Ok, I'd call that pretty much "solved". Sure, it's still visible, but
> for being a benchmark that apparently does little else than pound on
> those sysv semaphores, I think we can consider it pretty much fine.
> I'm going to assume that anybody who actually then does any real work
> (ie a database) is never going to see even close to this bad
> contention.
>
> Good job, Rik. I'm assuming we'll be merging this during the 3.10
> merge window, and hopefully the merge conflicts will be sorted out
> too. Rik, Peter, can you look at each others patches and see if you
> can get that sorted out for Andrew?

Will do.

I will rebase this series on top of what is in linux-next.

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