Re: speed of COW directory copying: XFS 20x slower than ext3
> > it turned out the problem is in the XFS filesystem, that is 20x slower,
> > than the ext3 filesystem. I know that XFS is bad at handling small
> > files, but 20x times?
>
> Try to play with parameters mentioned in laptop-mode.txt in the Linux
> sources.
>
> Then, try to have XFS log area on separate device. This can boost
> performance, because log data will be accessed and/or written in
> parallel (by hardware) to actual file system operation.
>
> I think very vivid data is: http://oss.oracle.com/~mason/seekwatcher
>
> I have my speed test nearly a year ago. Ext3 have big speed, until it
> starts writing caches from RAM to actual device.
Thanks for the suggestions, I looked into the laptop-mode.txt. I just
don't have time to play with all those parameters. I just want to
install it by default and either it is fast, or it is not. So my
conclusion is:
Use xfs with -o nobarrier or ext3.
Ondrej
P.S. I am copying what I post to Debian mentors only:
We just discovered, that mounting XFS partition with:
sudo mount -o nobarrier /dev/sda2 /mnt/p1
speeds things up on all machines. The reason is, that the option "-o
barrier" was added by default to all kernels >= 2.6.17, so dakol has
nobarrier, all the others have barrier. By mounting with nobarrier,
the cp and rm times are 5s on the first run and around 1.7s on
subsequent runs. That's much better for XFS.
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