Re: Regression in reading /proc/stat in the newer kernels with large SMP and NUMA configurations

From: Laurence Oberman
Date: Mon Dec 05 2011 - 16:38:39 EST


Laurence Oberman <laurence.oberman <at> hp.com> writes:

>
>
> Eric Dumazet <eric.dumazet <at> gmail.com> writes:
>
> Hi Eric,
>
> I finally managed to get some time to test the patch. I am testing on the
> generic kernel.org 2.6.39 tree and will update you as soon as possible.
>
> Thanks
> Laurence
>
>

Hello,
Results are in, patch makes a huge difference:

We are now getting results in the usecs again.


[root@o184i026 lobe]# strace -c ./t
Opened, read and closed 8640 times and read total of 69819840 bytes
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
99.86 0.964056 112 8641 read
0.08 0.000786 0 8642 open
0.06 0.000554 0 8642 close
0.00 0.000034 4 8 mmap
0.00 0.000000 0 1 write
0.00 0.000000 0 3 fstat
0.00 0.000000 0 3 mprotect
0.00 0.000000 0 1 munmap
0.00 0.000000 0 1 brk
0.00 0.000000 0 1 ioctl
0.00 0.000000 0 1 1 access
0.00 0.000000 0 1 execve
0.00 0.000000 0 1 arch_prctl
------ ----------- ----------- --------- --------- ----------------
100.00 0.965430 25946 1 total

What do you need me to do to get your patch accepted.

Thanks
Laurence


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