Messages in this thread | | | Date | Fri, 11 Dec 2009 18:15:20 +0100 | Subject | Re: [PATCH] cfq-iosched: reduce write depth only if sync was delayed | From | Corrado Zoccolo <> |
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Hi Jeff, On Wed, Dec 9, 2009 at 7:09 PM, Jeff Moyer <jmoyer@redhat.com> wrote: > Corrado Zoccolo <czoccolo@gmail.com> writes: > >> The numbers look good. Now, there is no penalty in having low_latency >> set for sequential writes, and just a small penalty for random ones. >> The fact that random reads are faster with low_latency set is interesting. >> Is the test is running with your patched tiobench (so that the number >> of random operations is comparable with sequential ones)? > > No, I forgot all about that. The number of random operations defaults > to 4000, which is pretty low. I'll re-run the tests with a number > comparable to the sequential runs. Sorry about that. > N.P. if you have time, can you also re-run the test changing: iosched/fifo_expire_async to 8 ? I hope that reducing the expire_async, will make cfq quicker at switching between the different threads, allowing more parallelism for seq writers on your hw. If this is the case, I think I can try to estimate the fifo_expire_async in the autotuning patch.
> Cheers, > Jeff >
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