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> Hi, I'm experiencing some cfq/bfq performance issues too, but I'm > still not able to track down the reasons, so before posting on this > topic on the mailing list I'd ask you a couple of questions. > > 1) Are you running the hdparm performance test under some cpu load? > (Even two hdparm instances ran in parallel could do.) > > 2) Does using a bigger value of slice_idle increase the throughput? > Hi, 1) no it was always in (almost) complete idle 2) a bigger value even made it worse, setting it to "0" however seemingly "fixed" it, I however don't know how the overall effect/impact is, this will need some more real-world testing ;) cat /sys/block/sdd/queue/iosched/slice_idle 0 hdparm -t /dev/sdd /dev/sdd: Timing buffered disk reads: 314 MB in 3.01 seconds = 104.32 MB/sec hdparm -t /dev/sdd /dev/sdd: Timing buffered disk reads: 312 MB in 3.00 seconds = 103.86 MB/sec hdparm -t /dev/sdd /dev/sdd: Timing buffered disk reads: 314 MB in 3.01 seconds = 104.24 MB/sec one side-node / question: will this cause more wakeups on the cpu and/or decrease battery runtime on, e.g. laptops ? > Thank you very much, I'll try hdparm on my test boxes and come back > to the list if I find something on that. > > As a sidenote, Ingo is not the author/maintainer of cfq, maybe the > next time CC: Jens Axboe for that. > oops, didn't know that, thanks - didn't want to give the wrong person the "credits" hi & kudos to Jens ;) here's a nice site which explains all of the settings: http://www.nextre.it/oracledocs/ioscheduler_03.html Regards Mat | ||||||||||
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