sorry about many posts, i will stop a bit now... could we turn off disk NCQ? ok nobody want to read this, but could we turn off NCQ and get better performace? since we do a good elevator at linux code... maybe turn off disk cache too... (it´s only 32MB for sata/sas, and can be alot to raid controller...), just some ideas to get better performace... (i didn´t think before write if cache help or not when we send I/O to disk, but check if it´s a good question or not) 2012/7/2 Roberto Spadim <roberto@xxxxxxxxxxxxx>: > for SSD without inteligent parts (cache and queue) i think this could > works nice... (at least in theory) > for USB sticks and microsd cards may work too... > > > 2012/7/2 Shaohua Li <shli@xxxxxxxxxx>: >> On Sun, Jul 01, 2012 at 11:13:42PM -0300, Roberto Spadim wrote: >>> nice =) very very nice =) >>> maybe to get better than this... select the disk with min(pending time) >>> >>> time could be estimated with something like: >>> (distance * time/distance unit) + (blocks to read/write * time to >>> read/write 1 block) + (non sequencial penalty time) >> >> I didn't think there is way to measure request time. Disks support NCQ, they >> can dispatch several requests at one time and finish them almost at the same >> time. I used to measure this time (to make CFQ ioscheduler self tune), but >> failed. >> >> Thanks, >> Shaohua >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
