Re: I/O degredation with AS on 2.6.0-test3

[Nick Piggin]

Mike Sullivan wrote:

> > > Dave Hansen wrote:
> > >
> > > You might want to try Martin Bligh's diffprofile utility.  It's a bit
> > > hard to compare 2 500-line profiles without it.
> > >
> > > ftp://ftp.kernel.org/pub/linux/kernel/people/mbligh/tools/
> > >
> > > Also, there have evidently been a few I/O scheduler fixes since -test3.
> > > Please retry with -test5.
>
> > Nick Piggen wrote:
> > More important, are they regressions vs. previous kernels with AS?
>
> I've checked 2.5.69mm9, 2.5.75, 2.6.0test3, and 2.6.0test5 and they all
> show a
> significant degradation in IO performance (>40%) when using the as
> scheduler
> compared to the deadline scheduler.
>
> Configuration: IBM x440 8way with hypertheading enabled, 16GB RAM,
> 4 QLA2310 FC adapters attached to 2 FastT900 controllers
> (112 disks total). The 112 physical disks are striped as 8 raid 0
> logical disks. There are a total of 40 raw devices setup (5 per raid0
> disk).
>
> I've reattached excerpts from the database test for vmstat and
> the readprofile diffs created from Martin's diffprofile utility
> (diffprofile readp.as readp.dl).

Thanks Mike, I'll get a patch for you to try soon. I'm a bit busy ATM.


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