Messages in this thread | | | Date | Fri, 24 Jan 2003 13:33:07 +1100 | From | Nick Piggin <> | Subject | Re: big ext3 sequential write improvement in 2.5.51-mm1 gone in 2.5.53-mm1? |
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Andrew Morton wrote:
>rwhron@earthlink.net wrote: > >>Did you add a secret sauce to 2.5.59-mm2? >> > >I have not been paying any attention to the I/O scheduler changes for a >couple of months, so I can't say exactly what caused this. Possibly Nick's >batch expiry logic which causes the scheduler to alternate between reading >and writing with fairly coarse granularity. > Yes, however tiobench doesn't mix the two. The batch_expire helps probably by giving longer batches between servicing expired requests. The deadline-np-42 patch also eliminates corner cases in which requests could be starved for a long time. A large batch_expire as in mm2 is not a good solution without my anticipatory scheduling stuff though as writes really starve reads.
> > >> 10x sequential write improvement on ext3 for multiple tiobench threads. >> > >OK... > >I _have_ been paying attention to the IO scheduler for the past few days. >-mm5 will have the first draft of the anticipatory IO scheduler. This of >course is yielding tremendous improvements in bandwidth when there are >competing reads and writes. > >I expect it will take another week or two to get the I/O scheduler changes >really settled down. Your assistance in thoroughly benching that would be >appreciated. > > >>2.4.20aa1 8.24 7.21% 28.587 449134.11 0.10395 0.07086 114 >>2.5.59 9.50 5.50% 36.703 4310.62 0.00000 0.00000 173 >>2.5.59-mm2 35.28 17.69% 10.173 18950.56 0.01010 0.00000 199 >> > >boggle. > I'm happy with that as long as they aren't too dependant on the phase of the moon. The initial deadline scheduler had quite a lot of problems with these workloads.
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