Re: [Qemu-devel] [patch 0/5][v2] qcow2: improve I/O performance with cache=off

[Anthony Liguori <anthony@codemonkey.ws>]

Laurent Vivier wrote:
> Le mardi 29 juillet 2008 à 14:15 -0500, Anthony Liguori a écrit :
>   
>> Laurent Vivier wrote:
>>     
>>> These patches improve qcow2 performance when used with cache=off.
>>>
>>> They modify block-qcow2.c to read/write as many clusters as
>>> possible per bdrv_aio_[read|write]().
>>>   
>>>       
>> This patch series looks like a pretty good clean up of the code.  The 
>> perf improvement is a nice side effect too.
>>
>> I'm a little concerned about how much code this touches though.  How 
>>     
>
> Yes, I know, it's why I split it in several patches: easier to review,
> easier to test.
>
>   
>> much testing have you done of these changes?  Have you tested all of the 
>> corner cases (backing files, filling up a disk image, etc.)?
>>     
>
> Well, before all I made a lot of review of my modifications, but it must
> also be reviewed by other eyes.
>
> I think it covers a lot of cases, but I didn't test encrypted disk image
> and compressed disk image. The case with backed files was tested only
> with mkfs/fsck/dbench.
>
> If you think these patches are good candidates to be included, I can
> make more tests.
>   

Yes, I do think these patches make sense.  I would like to see more 
testing though.  It all seemed pretty clear to me (breaking out the 
patches was very helpful!) but I am very worried about corrupting qcow2 
images.

Regards,

Anthony Liguori

> Regards,
> Laurent
>