cpio to ext4 seems much slower than to ext2, ext3 or xfs

[Dennis J.]

On 11/12/2009 04:03 PM, Eric Sandeen wrote:
> Richard W.M. Jones wrote:
>> On Thu, Nov 12, 2009 at 09:54:12AM +0000, Daniel P. Berrange wrote:
>>> On Wed, Nov 11, 2009 at 09:05:20PM +0000, Richard W.M. Jones wrote:
>>>> On Wed, Nov 11, 2009 at 01:24:20PM -0600, Eric Sandeen wrote:
>>>>> Anybody got actual numbers? I don't disagree that mkfs.ext4 is slow
>>>>> in the default config, but I don't think it should be slower than
>>>>> mkfs.ext3 for the same sized disks.
>>>> Easy with guestfish:
>>>>
>>>> $ guestfish --version
>>>> guestfish 1.0.78
>>>> $ for fs in ext2 ext3 ext4 xfs jfs ; do guestfish sparse
>>>> /tmp/test.img 10G : run : echo $fs : sfdiskM /dev/sda , : time mkfs
>>>> $fs /dev/sda1 ; done
>>>> ext2
>>>> elapsed time: 5.21 seconds
>>>> ext3
>>>> elapsed time: 7.87 seconds
>>>> ext4
>>>> elapsed time: 6.10 seconds
>>>> xfs
>>>> elapsed time: 0.45 seconds
>>>> jfs
>>>> elapsed time: 0.78 seconds
>>>>
>>>> Note that because this is using a sparsely allocated disk each write
>>>> to the virtual disk is very slow. Change 'sparse' to 'alloc' to test
>>>> this with a non-sparse file-backed disk.
>>> You really want to avoid using sparse files at all when doing any
>>> kind of
>>> benchmark / performance tests in VMs. The combo of a sparse file
>>> store on
>>> a journalling filesystem in the host, w/ virt can cause very
>>> pathelogically
>>> bad I/O performance until the file has all its extents fully
>>> allocated on
>>> the host FS. So the use of a sparse file may well be exagarating the
>>> real
>>> difference in elapsed time between these different mkfs calls in the
>>> guest.
>>
>> Again, this time backed by a 10 GB logical volume in the host, so this
>> should remove pretty much all host effects:
>>
>> $ for fs in ext2 ext3 ext4 xfs jfs reiserfs nilfs2 ntfs msdos btrfs
>> hfs hfsplus gfs gfs2 ; do guestfish add /dev/mapper/vg_trick-Temp :
>> run : zero /dev/sda : echo $fs : sfdiskM /dev/sda , : time mkfs $fs
>> /dev/sda1 ; done
>
>
>> ext2
>> elapsed time: 3.48 seconds
>
>> ext3
>> elapsed time: 5.45 seconds
>> ext4
>> elapsed time: 5.19 seconds
>
> so here we have ext4 slightly faster, which was the original question... ;)
>
> (dropping caches in between might be best, too...)
>
>> xfs
>> elapsed time: 0.35 seconds
>> jfs
>> elapsed time: 0.66 seconds
>> reiserfs
>> elapsed time: 0.73 seconds
>> nilfs2
>> elapsed time: 0.19 seconds
>> ntfs
>> elapsed time: 2.33 seconds
>> msdos
>> elapsed time: 0.29 seconds
>> btrfs
>> elapsed time: 0.16 seconds
>> hfs
>> elapsed time: 0.44 seconds
>> hfsplus
>> elapsed time: 0.46 seconds
>> gfs
>> elapsed time: 1.60 seconds
>> gfs2
>> elapsed time: 3.98 seconds
>>
>> I'd like to repeat my proviso: I think this test is meaningless for
>> most users.
>
> Until users have 8TB raids at home, which is not really that far off ...

Let's hope btrfs is production ready before then because extX doesn't look 
like a fitting filesystem for such big drives due their lack of online fsck.

Regards,
   Dennis