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Date: Mon, 12 Mar 2012 14:36:50 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/4] block: add image fragmentation
 statistics to qemu-img
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>, qemu-devel@nongnu.org, stefanha@linux.vnet.ibm.com

Am 12.03.2012 14:26, schrieb Stefan Hajnoczi:
> On Mon, Mar 12, 2012 at 1:14 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>> Am 12.03.2012 14:07, schrieb Stefan Hajnoczi:
>>> On Wed, Mar 7, 2012 at 9:22 AM, Dong Xu Wang <wdongxu@linux.vnet.ibm.com> wrote:
>>>> @@ -1126,6 +1127,14 @@ static int img_info(int argc, char **argv)
>>>>             printf("cluster_size: %d\n", bdi.cluster_size);
>>>>         }
>>>>     }
>>>> +    if (bdrv_get_fragment(bs, &bfi) >= 0) {
>>>
>>> I think we need a separate sub-command for fragmentation info:
>>>
>>> qemu-img fraginfo <image-file>
>>>
>>> Utilities that invoke qemu-img info want it to be fast.  Reading all
>>> metadata from a large image can take several seconds.  Since many
>>> qemu-img info users don't need to see the fragmentation information,
>>> it makes sense to put it in a new sub-command.
>>
>> Yes. If we wanted to merge it into an existing qemu-img subcommand, I
>> think check would be the one, as it scans the whole image already today
>> and fragmentation is something that could be added fairly easily.
> 
> In that case we might not even need a separate interface/struct.  This
> would just be part of check.
> 
> Does that sound good?

Sure, that would be the only way to take advantage of the scan that
bdrv_check already performs.

Kevin