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

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Message-ID: <CA+55aFzRsjj6Tc452EcCFsNmXk+t=AkuzxKuy-AVV3RjUssB_g@mail.gmail.com>
Date:	Wed, 20 Mar 2013 13:56:12 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Rik van Riel <riel@...riel.com>
Cc:	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 Wed, Mar 20, 2013 at 1:49 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> It *would* be lovely to see this run with the actual Swingbench
> numbers. The microbenchmark always looked much nicer. Do the
> additional multi-semaphore scalability patches on top of Davidlohr's
> patches help with the swingbench issue, or are we still totally
> swamped by the ipc lock there?
>
> Maybe there were already numbers for that, but the last swingbench
> numbers I can actually recall was from before the finer-grained
> locking..

Ok, and if the spinlock is still a big deal even with the finer
granularity, it might be interesting to hear if Michel's fast locks
make a difference. I'm guessing that this series might actually make
it easier/cleaner to do the semaphore locking using another lock,
since the ipc_lock got split up and out...

I think Michel did it for some socket code too. I think that was
fairly independent and was for netperf.

            Linus
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