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

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Date:	Mon, 5 Dec 2011 21:38:18 +0000 (UTC)
From:	Laurence Oberman <laurence.oberman@...com>
To:	linux-kernel@...r.kernel.org
Subject: Re: Regression in reading /proc/stat in the newer kernels with large SMP and NUMA configurations

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@...4i026 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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