Tell me more ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.
up vote 1 down vote favorite

I did 4 clean installations of debian 6 and measured time of installing some average virtual package. FS options are default.

time apt-get install build-essential

I got very strange results (min:sec, less is faster):

XFS:   3:12
btrfs: 2:45
ext3:  0:30
ext4:  0:50

What the flying flock wrong with the first two? 6 times slower than ext3? Am I doing something wrong?

enter image description here

Upd (some details):

All LVM volumes are local to VM and are on idle RAID. CDROM image is local and the same, Internet connection is stable and it factors max 10-15 seconds. All the visible slowdowns are after downloads: XFS and btrfs guests think over 1 second every Unpacking. Low-level caching is disabled. Host node is idle every installation, no active guests but the one.

share|improve this question
2  
I see you are using VMs, how do you factor out contention with other VMs? Are you sure you didn't have something else running at the same time as your XFS test? Did you pre-download, have a local APT cache, or a CD-ROM image so you can factor out any issues with retrieving packages from the random mirror you would get from the Internet? – Zoredache May 23 '12 at 19:34
I'd add to this that some amount of lower level caching would likely take place unless the storage is unmounted and remounted between each individual run... – rnxrx May 23 '12 at 19:55
I fail to notice any factor that could drop performance even 2 times. All LVM volumes are local to VM and are on idle RAID. CDROM image is local and the same, Internet connection is stable and it factors max 10-15 seconds. All the visible slowdowns are after downloads: XFS and btrfs guests think over 1 second every Unpacking. Low-level caching is disabled. I decided to run these tests because I was unhappy with package manager performance on metal host. – ujifgc May 24 '12 at 5:44
@ujifgc: Unhappy with package manager performance? apt too slow? Try installing bigger stuff with Gentoo's Portage or *BSD ports and talk about waiting ... :-) that said, mount options such as barrier=0 might help with XFS -- ext3 does not enable that by default, unless things have changed recently. – Janne Pikkarainen May 24 '12 at 8:46
1  
FYI, my own tests also show a huge discrepancy between btrfs and ext4 (running apt on ext4 vs btrfs; I did not test ext3 or xfs). – Stefan Lasiewski Jun 16 '12 at 19:19
show 4 more comments

Know someone who can answer? Share a link to this question via email, Google+, Twitter, or Facebook.

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.