On Fri, Jan 05, 2007 at 04:19:48PM -0600, Dave Lloyd wrote:
> From a co-worker. Anyone know what might have changed this between
> 2.6.18 and 2.6.19 when the issue first appeared?
IIRC< a bunch of changes went into the generic buffered I/O
path to fix deadlocks on writes if we take a page fault during
the copyin. That caused a performance regression for buffered
I/O of around that sort of figure, and the regression is slowly
being fixed up as per:
> under 2.6.20-rc3 the speeds have gone back up some, but they are 10%
> slower than 2.6.18.
So I don't think this is an XFS problem as such. Still, I will try
to do some local tests to check it out.
> and the allocations, as shown by the sequential writes (attached) are
> random.
????
> If I went all the way out to the inside tracks, you would be at about
> 490MB/Sec.
>
> Something changed. 2.6.19 was unstable, with XFS panics on a regular basis.
Got any stack traces?
> 2.6.19.1 has not had an error yet.. (knock head on wall repeatedly).
We didn't push any changes into 2.6.19.1, so that implies bugs in
the generic code, not XFS....
Cheers,
Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
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