From: Ingo Molnar <mingo@elte.hu>
To: Dinakar Guniguntala <dino@in.ibm.com>
Cc: linux-kernel@vger.kernel.org, david singleton <dsingleton@mvista.com>
Subject: Re: Perf degradation from -rt14 onwards
Date: Thu, 1 Dec 2005 22:21:05 +0100 [thread overview]
Message-ID: <20051201212105.GA25686@elte.hu> (raw)
In-Reply-To: <20051201204227.GA16035@in.ibm.com>
* Dinakar Guniguntala <dino@in.ibm.com> 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.
nice catch! I've undone this change in my tree.
Ingo
prev parent reply other threads:[~2005-12-01 21:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-01 20:42 Perf degradation from -rt14 onwards Dinakar Guniguntala
2005-12-01 20:59 ` David Singleton
2005-12-01 21:21 ` Ingo Molnar [this message]
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