Mingming Cao [off-list ref] wrote:

On Sat, 2003-06-14 at 01:01, Andrew Morton wrote:

quoted

Was elevator=deadline observed to fail in earlier kernels?  If not then it
may be an anticipatory scheduler bug.  It certainly had all the appearances
of that.

Yes, with elevator=deadline the many fsx tests failed on 2.5.70-mm5.
 

quoted

So once you're really sure that elevator=deadline isn't going to fail,
could you please test elevator=as?

Ok, the deadline test was run for 10 hours then I stopped it (for the
elevator=as test).  

But the test on elevator=as (2.5.70-mm9 kernel) still failed, same
problem.  Some fsx tests are sleeping on io_schedule().  

Next I think I will re-run test on elevator=deadline for 24 hours, to
make sure the problem is really gone there.  After that maybe try a
different Qlogic Driver, currently I am using the driver from Qlogic
company(QLA2XXX V8).

Martin has just observed what appears to be the same failure on
2.5.71-mjb1, which is the deadline scheduler, using qlogicisp.

Again, some IO appears to have been submitted but it never came back.

It could be a bug in the requests queueing code somewhere, or in the device
driver.

So a good thing to do now would be to find the workload+IO
scheduler+filesystem which triggers it most easily, and run that with a
different device driver.  The feral driver (drivers/scsi/isp/ in -mm)
should be suitable for that test.

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