rawhide ext4/virtio FS performance hit (10x slower) ?

[drago01]

On Sat, May 12, 2012 at 11:04 PM, Jim Meyering <jim at meyering.net> wrote:
> Josh Boyer wrote:
>
>> On Mon, May 7, 2012 at 8:43 AM, Jim Meyering <jim at meyering.net> wrote:
>>> Today I noticed that some tests from coreutils' test suite
>>> were taking far longer than they used to on rawhide.
>>> For example, run this command in an empty directory:
>>>
>>>  seq 200000|env time xargs touch
>>>
>>> it takes < 5s on F17 3.3.4-1.fc17.x86_64 ext4/sdb8/SSD, yet
>>> it takes 47s on rawhide 3.4.0-0.rc5.git5.1.fc18.x86_64 ext4/vda1/SSD
>>>
>>> 10x performance hit... ouch.
>>>
>>> Does anyone know why?
>>
>> Rawhide has all the kernel debug options turned on.  It isn't
>> worthwhile doing a comparison when those are enabled.  You could try
>> again with the first -rc6 build that shows up, as that will have the
>> options disabled.
>
> Hi Josh,
>
> I've just rerun the test with 3.4.0-0.rc6.git1.1.fc18.x86_64,

This one has debug options enabled; 3.4.0-0.rc6.git0.1 is the one
without debug options.