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

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Message-ID: <CA+i8gKJuykoCk=O3qbDmmZXd=8U13wF7o_NzUviccaZoU6WLaA@mail.gmail.com>
Date:	Sun, 24 Mar 2013 20:46:38 +0700
From:	Emmanuel Benisty <benisty.e@...il.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Rik van Riel <riel@...riel.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	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>
Subject: Re: ipc,sem: sysv semaphore scalability

On Sun, Mar 24, 2013 at 2:45 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Fri, Mar 22, 2013 at 8:19 PM, Emmanuel Benisty <benisty.e@...il.com> wrote:
>>
>> I could reproduce it but could you please let me know what would be
>> the right tools I should use to catch the original oops?
>> This is what I got but I doubt it will be helpful:
>> http://i.imgur.com/Mewi1hC.jpg
>
> In this case, I think the best thing to do would be to comment out all
> of drm_warn_on_modeset_not_all_locked(), because those warnings make
> the original problem (that probably caused the lock problem in the
> first place that it is warning about) scroll away.
>
> That said, you should also take the oneliner fix that Rik posted to
> patch 7 (subject line: "[PATCH 7/7 part3] fix for sem_lock") and apply
> that, just to make sure that you aren't possibly hitting a bug with
> the shared-memory locking introduced by that (unusual) case.

Thanks Linus. I hope I got this right, here's the result (3.9-rc4, 7+1
patches): http://i.imgur.com/BebGZxV.jpg
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