Re: Perf degradation from -rt14 onwards

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux