Re: XFS performance issues: O_DIRECT and Linux 2.6.6+

[James Foris <james.foris@xxxxxxxxxx>]

Nathan Scott wrote:
> Hi James,
>
> On Mon, Sep 13, 2004 at 11:56:33AM -0500, James Foris wrote:
>
> > More correctly, it happened between 2.6.5 and 2.6.5-bk1
> >
> > So..... something in the 2.6.5-bk1 patchset caused the change.
> > Any suggestions where to begin looking (other than fs/direct_io.x) ?
>
> http://kernel.org/pub/linux/kernel/v2.6/snapshots/old/patch-2.6.5-bk1.log
Yup... a bunch more.

"Major surgery against the pagecache, radix-tree and writeback code"

The interesting question is; why do XFS and REISER suffer under O_DIRECT
when other file systems improve?  And why does s/w RAID0 with an external
journal suffer much worse than a simple file system with an internal journal?

Do these questions suggest anyplace else to look ?

Jim Foris

> search for "direct" -- looks like -bk1 includes all the changes I
> was refering to earlier (and a bunch more) :(  So, the needle is
> somewhere in that haystack...
>
> cheers.