Re: Awful Raid10,f2 performance

["Keld Jørn Simonsen" <keld@dkuug.dk>]

On Tue, Dec 16, 2008 at 09:53:39AM -0600, Jon Nelson wrote:
> On Tue, Dec 16, 2008 at 9:26 AM, Jon Nelson
> <jnelson-linux-raid@jamponi.net> wrote:
> > On Tue, Dec 16, 2008 at 4:10 AM, Keld Jørn Simonsen <keld@dkuug.dk> wrote:
> >> On Mon, Dec 15, 2008 at 10:28:30PM -0600, Jon Nelson wrote:
> >>> On Mon, Dec 15, 2008 at 10:03 PM, Keld Jørn Simonsen <keld@dkuug.dk> wrote:
> >>>
> >>> > there was a pach to speed up raid10,f2 check in a recent kernel,
> >>> > something like 2.6.27. It did improve thruput from something
> >>> > like 40 % to about 90 %. What kernel are you using?
> >>>
> >>> 2.6.25.18-0.2-default
> >>
> >> I believe the patch arrived in a later kernel. If you can try it out
> >> with a vanilla kernel and report, I think it would be quite interesting.
> >
> > I'm pretty sure I did try it out and did have an improvement.
> > However, thanks to the power of the openSUSE build service, I am going
> > to build a kernel just now, if I can.
> 
> Scratch that. I decided to just do this at home. The suse kernel
> 2.6.25.18-0.2 appears to have this patch already. Thus, I've been
> running with this patch.

OK, well, then the patch did not apply to check, but only to resync.
One could write up a similar patch for check as what was done for
resync. The idea of the previous patch was to read quite much data in a
striped way, say 10 - 20 MB at a time.

best regards
keld
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