Re: Performance regression in IO scheduler still there

Corrado Zoccolo
2009-11-16T18:38:02Z

On Mon, Nov 16, 2009 at 6:03 PM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Jan Kara <jack@suse.cz> writes:
>
>> On Mon 16-11-09 11:47:44, Jan Kara wrote:
>>   OK, here are the numbers (3 runs of each test):
>> 2.6.29:
>> Threads       Avg             Stddev
>> 1     42.043333       0.860439
>> 2     40.836667       0.322938
>> 4     41.810000       0.114310
>> 8     40.190000       0.419603
>> 16    39.950000       0.403072
>> 32    39.373333       0.766913
>>
>> 2.6.32-rc7:
>> Threads       Avg             Stddev
>> 1     41.580000       0.403072
>> 2     39.163333       0.374641
>> 4     39.483333       0.400111
>> 8     38.560000       0.106145
>> 16    37.966667       0.098770
>> 32    36.476667       0.032998
>>
>>   So apparently the difference between 2.6.29 and 2.6.32-rc7 increases as
>> the number of threads rises. With how many threads have you been running
>> when using SATA drive and what machine is it?
>>   I'm now running a test with larger file size (8GB instead of 4) to see
>> what difference it makes.
>
> I've been running with both 8 and 16 threads.  The machine has 4 CPUs
> and 4GB of RAM.  I've been testing with an 8GB file size.

Other details may be relevant, e.g.the file system on which the file
is located, whether the caches are dropped before starting each run,
and so on.

Corrado

>
> Cheers,
> Jeff
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