Messages in this thread | | | Date | Thu, 17 Apr 2008 13:30:47 +0200 | From | Fabio Checconi <> | Subject | Re: [RESEND][RFC] BFQ I/O Scheduler |
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> From: Jens Axboe <jens.axboe@oracle.com> > Date: Thu, Apr 17, 2008 11:27:55AM +0200 > > On Thu, Apr 17 2008, Paolo Valente wrote: > > Maybe there is also another middle-ground solution. I'll try to sketch ... > > Does it seem reasonable? > > Not for CFQ, that will stay time based. The problem with #2 above is > that it then quickly turns to various heuristics, which is just > impossible to tune for general behaviour. Or it just falls apart for > other real life situations. >
Ok.
After a brief offline discussion with paolo, here it is what we can do:
o propose a patch for discussion that uses our WF2Q+ variant to schedule timeslices in cfq. The resulting scheduler would be quite close to the EEVDF scheduler discussed some time ago for the cpu.
o Introduce a timeout in bfq to give an upper time limit to the slices. Since we have not experimented with that mixed approach before[*], we will need to do some tests with relevant workloads to see if/how it can work.
I fear that it will take some time, as we're both travelling in this week.
[*] Anyway it is quite close to how cfq handles async queues, with their slice_async and slice_async_rq, so it's definitely not something new.
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