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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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.

Regards,
Daniel
-- 
|: Red Hat, Engineering, London   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|

-- 
fedora-devel-list mailing list
fedora-devel-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/fedora-devel-list

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Fedora Announce]     [Fedora Kernel]     [Fedora Testing]     [Fedora Formulas]     [Fedora PHP Devel]     [Kernel Development]     [Fedora Legacy]     [Fedora Maintainers]     [Fedora Desktop]     [PAM]     [Red Hat Development]     [Gimp]     [Yosemite News]
  Powered by Linux