Messages in this thread | | | Date | Fri, 20 Sep 2002 19:31:03 +0200 | From | Jens Axboe <> | Subject | Re: TPC-C benchmark used standard RH kernel |
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On Fri, Sep 20 2002, Mike Anderson wrote: > > Dave Hansen [haveblue@us.ibm.com] wrote: > > Bond, Andrew wrote: > > > This isn't as recent as I would like, but it will give you an idea. > > > Top 75 from readprofile. This run was not using bigpages though. > > > > > > 00000000 total 7872 0.0066 > > > c0105400 default_idle 1367 21.3594 > > > c012ea20 find_vma_prev 462 2.2212 > > > > c0142840 create_bounce 378 1.1250 > > > c0142540 bounce_end_io_read 332 0.9881 > > .. snip.. > > > > Forgive my complete ignorane about TPC-C... Why do you have so much > > idle time? Are you I/O bound? (with that many disks, I sure hope not > > :) ) Or is it as simple as leaving profiling running for a bit before > > or after the benchmark was run? > > The calls to create_bounce and bounce_end_io_read are indications that > some of your IO is being bounced and will not be running a peak > performance. > > This is avoided by using the highmem IO changes which I believe are not > in the standard RH kernel. Unknown if that would address your idle time > question.
They benched RHAS iirc, and that has the block-highmem patch. They also had more than 4GB of memory, alas, there is bouncing. That doesn't work on all hardware, and all drivers.
-- Jens Axboe
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