linux-kernel - Re: [PATCH 1/2] ipc semaphores: reduce ipc

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Message-ID: <20100415163455.GD3794@think>
Date:	Thu, 15 Apr 2010 12:34:55 -0400
From:	Chris Mason <chris.mason@...cle.com>
To:	Manfred Spraul <manfred@...orfullife.com>
Cc:	Nick Piggin <npiggin@...e.de>, zach.brown@...cle.com,
	jens.axboe@...cle.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] ipc semaphores: reduce ipc_lock contention in
 semtimedop

On Thu, Apr 15, 2010 at 06:33:13PM +0200, Manfred Spraul wrote:
> On 04/14/2010 09:50 PM, Chris Mason wrote:
> >On a big system I saw about 4000 semaphores total.  The database will
> >just allocate as many as it can into a single array and keep creating
> >arrays until it has all it needs.
> >
> What happens if SEMMSL is reduced (first entry in /proc/sys/kernel/sem)?

Performance improves slightly but the ipc lock is still at the top of the
profile ;)

-chris

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