linux-kernel - Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4

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Message-ID: <20071205210222.GA30089@elte.hu>
Date:	Wed, 5 Dec 2007 22:02:22 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Jie Chen <chen@...b.org>
Cc:	Simon Holm Th??gersen <odie@...aau.dk>,
	Eric Dumazet <dada1@...mosbay.com>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4


* Jie Chen <chen@...b.org> wrote:

>> sorry to be dense, but could you give me instructions how i could 
>> remove the affinity mask and test the "barrier overhead" myself? I 
>> have built "pthread_sync" and it outputs numbers for me - which one 
>> would be the barrier overhead: Reference_time_1 ?
>
> To disable affinity, do configure --enable-public-release 
> --disable-thread_affinity. You should see barrier overhead like the 
> following: Computing BARRIER time
>
> Sample_size  Average     Min    Max          S.D.        Outliers
>  20      19.486162   19.482250   19.491400    0.002740      0
>
> BARRIER time =        19.486162 microseconds +/- 0.005371
> BARRIER overhead =    8.996257 microseconds +/- 0.006575

ok, i did that and rebuilt. I also did "make check" and got 
src/pthread_sync which i can run. The only thing i'm missing, if i run 
src/pthread_sync, it outputs "PARALLEL time":

 PARALLEL time =                           22.486103 microseconds +/- 3.944821
 PARALLEL overhead =                       10.638658 microseconds +/- 10.854154

not "BARRIER time". I've re-read the discussion and found no hint about 
how to build and run a barrier test. Either i missed it or it's so 
obvious to you that you didnt mention it :-)

	Ingo
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