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SubjectRe: Perf degradation from -rt14 onwards
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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