Re: [Qemu-devel] Greate difference of disk I/O performance for guest on Qemu-2.30 of CentOS.

[cauchy-love <cauchy-love@163.com>]

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Hi, Paolo,


   Sorry, but I don't know what does bisect mean exactly. Could you please explain it? I feel it might be some kernel configuration items introduce this problem. I am also trying other kernel versions from 2.6.34 to 2.6.38 (2.6.33.3 has good performance like 2.6.32) and will show you the results.


Thanks,


Yi








At 2015-06-24 20:20:02, "Paolo Bonzini" <pbonzini@redhat.com> wrote:
>
>
>On 24/06/2015 14:14, cauchy-love wrote:
>>     I have updated the kernel of CentOS 6.5 from 2.6.32 to higher
>> versions (2.6.39+) and found the disk IO write performance of my guest
>> OS degraded significantly (around 1/10 of 2.6.32) while read performance
>> was not influenced. That means everything is the same (i.e., hardware
>> configurations, BIOS, filesystems (ext4)) except the kernel. I would be
>> greatly apprieciated if you can provide some help about debugging this
>> problem. I have tried to trace the qemu but didn't get any progress.
>
>Can you bisect it further between 2.6.32 and 2.6.39?
>
>Stefan, does it ring any bell?
>
>Paolo

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