cfq: always return false from should_idle if slice_idle is set to zero
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From: Jens Axboe on 21 Jun 2010 16:10 On 21/06/10 21.49, Jeff Moyer wrote: > Hi, > > In testing a competing fsync-ing process and a sequential reader on > mid-grade storage, I found that cfq was incapable of achieving the I/O > rates of deadline, no matter how it was tuned. Investigation, and insight > from Vivek (mostly the latter), led to identifying that we were still > idling for the last queue in the service tree. > > Modifying cfq_should_idle to not idle when slice_idle is set to zero got > us much closer to the performance of deadline for this workload. I have > one follow-on patch that gets us on-par with deadline, but I think this > patch stands alone. > > Comments, as always, are appreciated. This looks good. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jens Axboe on 28 Jun 2010 15:00
On 28/06/10 20.41, Jeff Moyer wrote: > Jens Axboe <axboe(a)kernel.dk> writes: > >> On 21/06/10 21.49, Jeff Moyer wrote: >>> Hi, >>> >>> In testing a competing fsync-ing process and a sequential reader on >>> mid-grade storage, I found that cfq was incapable of achieving the I/O >>> rates of deadline, no matter how it was tuned. Investigation, and insight >>> from Vivek (mostly the latter), led to identifying that we were still >>> idling for the last queue in the service tree. >>> >>> Modifying cfq_should_idle to not idle when slice_idle is set to zero got >>> us much closer to the performance of deadline for this workload. I have >>> one follow-on patch that gets us on-par with deadline, but I think this >>> patch stands alone. >>> >>> Comments, as always, are appreciated. >> >> This looks good. > > So.... applied to which branch? Not applied yet, unless I explicitly say it's applied, then it's not necessarily in any public git tree yet. But this will go into .35. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |