Messages in this thread | | | Date | Sat, 10 Oct 2009 10:01:17 +0200 | From | Jens Axboe <> | Subject | Re: fio rand read/write regression with 2.6.32-rc3 |
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On Sat, Oct 10 2009, Zhang, Yanmin wrote: > Comparing with 2.6.23-rc1's result, fio rand read write has regression > on my 2*4 core stoakley machine (8GB memory) with a JBOD of 12 disks. > > Every disk has 8 1-GB files. Start 8 sub-processes per disk and every > process random chooses a file on the disk to do 36 times of file read or > write on the file and then choose another file. > > > fio_mmap_rand_read_4k regresion is about 35%.
Heh, I seem to recollect I told Linus that this would cost is 30-40% performance. So not totally crazy.
So yes, this isn't hugely unexpected. If you send me your fio job files, I'll try and see what I can do about it.
> Bisect down to patch: > 1d2235152dc745c6d94bedb550fea84cffdbf768 is first bad commit > commit 1d2235152dc745c6d94bedb550fea84cffdbf768 > Author: Jens Axboe <jens.axboe@oracle.com> > Date: Fri Oct 2 19:27:04 2009 +0200 > > cfq-iosched: add a knob for desktop interactiveness > > > After I revert the patch against 2.6.23-rc3, fio_mmap_rand_read_4k regression > disappears. > > fio_mmap_randrw_4k has less than 20% regression and reverting the patch > could restore performance. > > On another stoakley machine with another JBOD, we see the similiar regression. > > ffsb rand read/write has a bigger regression and reverting the patch > could restore performance. > > Yanmin > >
-- Jens Axboe
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