[Pvfs2-developers] kernel bug warning
robl at mcs.anl.gov
Fri Mar 24 11:19:33 EST 2006
On Fri, Mar 24, 2006 at 09:05:24AM +0100, Phil Carns wrote:
> I'm not sure exactly which kernels from kernel.org are affected, but we
> ran into a serious problem on the 2.6 kernel that we were using in RHEL4
> (2.6.9-22.0.1.ELsmp). The symptoms occur during a write-heavy
> workloads. From the PVFS2 point of view, write throughput on one or
> more servers will slow to just a few KB/s, and the AIO thread will
> consume 99% of cpu time.
Ugh. Thanks for tracking this down. I guess the only thing we can do
is add it to the FAQ?
> David Metheny and I spent a long time tracking this down. I highly
> recommend oprofile for debugging performance bugs like this. That was
> what finally clued us in to where the problem was after a variety of
> wrong turns :)
Glad to hear oprofile paid off!
Mathematics and Computer Science Division A215 0178 EA2D B059 8CDF
Argonne National Labs, IL USA B29D F333 664A 4280 315B
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