linux-kernel - Re: Scalability requirements for sysv ipc

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Date:	Sat, 22 Mar 2008 11:10:14 +0100
From:	Manfred Spraul <manfred@...orfullife.com>
To:	Mike Galbraith <efault@....de>
CC:	paulmck@...ux.vnet.ibm.com, Nadia Derbey <Nadia.Derbey@...l.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: Scalability requirements for sysv ipc

Mike Galbraith wrote:
> taskset -c 3 ./ctx -s 
>
> 2.6.24.3
> 3766962 itterations in 9.999845 seconds = 376734/sec
>
> 2.6.22.18-cfs-v24.1
> 4375920 itterations in 10.006199 seconds = 437330/sec
>
> for i in 0 1 2 3; do taskset -c $i ./ctx -s& done
>
> 2.6.22.18-cfs-v24.1
> 4355784 itterations in 10.005670 seconds = 435361/sec
> 4396033 itterations in 10.005686 seconds = 439384/sec
> 4390027 itterations in 10.006511 seconds = 438739/sec
> 4383906 itterations in 10.006834 seconds = 438128/sec
>
> 2.6.24.3
> 1269937 itterations in 9.999757 seconds = 127006/sec
> 1266723 itterations in 9.999663 seconds = 126685/sec
> 1267293 itterations in 9.999348 seconds = 126742/sec
> 1265793 itterations in 9.999766 seconds = 126592/sec
>
>   
Ouch - 71% slowdown with just 4 cores. Wow.
Attached are my own testapps: one for sysv msg, one for sysv sem.
Could you run them? Taskset is done internally, just execute

$ for i in 1 2 3 4;do ./psem $i 5;./pmsg $i 5;done

Only tested on uniprocessor, I hope the pthread_setaffinity works as 
expected....

--
    Manfred

View attachment "pmsg.cpp" of type "text/plain" (4665 bytes)

View attachment "psem.cpp" of type "text/plain" (4841 bytes)