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



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


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