Re: Perf degradation from -rt14 onwards

[Ingo Molnar]

* Dinakar Guniguntala <dino@xxxxxxxxxx> 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
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