Re: request baset device mapper in Linux

[Jun'ichi Nomura]

Hi Lukas,

On 09/16/11 23:08, Lukas Hejtmanek wrote:
> On Thu, Sep 15, 2011 at 02:49:52PM -0400, Mike Snitzer wrote:
>> Does "with your patch" mean against 3.0.3 or the original 2.6.32 kernel?
>>
>> If you apply the patch to the 3.0.3 kernel do you regain the performance?
> 
> Unfortunately, the patch does not help with 3.0.3 kernel

Thanks for the additional testing.

So:

  2.6.32.36
    no-multipath:        2.8 GB/s
    multipath:           600 MB/s
    multipath w/ patch:  2.8-2.9 GB/s

  3.0.3
    no-multipath:        ??
    multipath:           2.5 GB/s
    multipath w/ patch:  2.5 GB/s(?)

Have you tried 3.0.3 without multipath?

> top looks like this:
>    63 root      20   0     0    0    0 S   38  0.0   0:16.65 kswapd1
>    18 root      20   0     0    0    0 R   32  0.0   0:14.38 kworker/4:0
>    19 root      20   0     0    0    0 R   30  0.0   0:20.88 ksoftirqd/4
>   153 root      20   0     0    0    0 R   29  0.0   0:14.46 kworker/4:2
>    62 root      20   0     0    0    0 S   22  0.0   0:09.44 kswapd0

dm-multipath itself does not use workqueue for normal I/Os.
So you might be hitting a different problem.

Thanks,
-- 
Jun'ichi Nomura, NEC Corporation
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