Message-ID: <438F6440.2010409@mvista.com>
Date: Thu, 01 Dec 2005 12:59:44 -0800
From: David Singleton <dsingleton@mvista.com>
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To: dino@in.ibm.com
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: Perf degradation from -rt14 onwards
References: <20051201204227.GA16035@in.ibm.com>
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Dinakar Guniguntala wrote:

>I was wondering why the following change was made from -rt14
>onwards.
>
>
>@@ -1634,7 +1531,7 @@ asmlinkage long sys_futex(u32 __user *ua
>                          int val3)
> {
>        struct timespec t;
>-       unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
>+       unsigned long timeout = 0;
>
>This was introduced in patch-2.6.14-rt13-rf3 by David.
>
>This seems to return spurious -ETIMEDOUT errors even in the
>non-robust code and results in userspace (glibc) retrying
>several mutex operations before it succeeds. I was chasing
>down a degradation of performance of some testcases and was
>able to fix those by reverting this change back.
>  
>

Yes.  The default timeout should be set to MAX_SCHEDULE_TIMEOUT, not zero.

David

>	-Dinakar
>
>  
>

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