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

[Nick Piggin <piggin@cyberone.com.au>]

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.