Message-ID: <51A38257.2020804@colorfullife.com>
Date: Mon, 27 May 2013 17:57:11 +0200
From: Manfred Spraul <manfred@colorfullife.com>
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To: Davidlohr Bueso <davidlohr.bueso@hp.com>
CC: Rik van Riel <riel@redhat.com>, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, hhuang@redhat.com,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 0/4] ipc/sem.c: Bug fixes, regression fixes, v3
References: <1369559335-13491-1-git-send-email-manfred@colorfullife.com> <1369601453.2259.15.camel@buesod1.americas.hpqcorp.net>
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Hi Davidlohr,

On 05/26/2013 10:50 PM, Davidlohr Bueso wrote:
>
> In lack of getting my swingbench DSS environment back, I ran these
> changes against the semop-multi program on my laptop. For 256 threads,
> with Manfred's patchset the ops/sec suffers around -7.3%.

Could you also check the performance of only patch#1?
I fear that it might be slower than all 4 together.

With regards to semop-multi:
Is this the tool?
http://marc.info/?l=linux-kernel&m=136208613626892&q=p3

I think the logic is the wrong:
Locking a semaphore is substraction, unlocking adding.
Thus multiple tasks can run in parallel - and the task switch code is 
never triggered.
Could you double check that the number of context switches matches the 
output?

I usually use this tool:
http://marc.info/?l=linux-kernel&m=125038376609750


--
     Manfred
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