Tejun Heo wrote: > Michael Tokarev wrote: [] >> A test drive is Seagate Barracuda ST3250620AS "desktop" drive, >> 250Gb, cache size is 16Mb, 7200RPM. [test shows that NCQ makes no difference whatsoever] > And which elevator? Well. It looks like the results does not depend on the elevator. Originally I tried with deadline, and just re-ran the test with noop (hence the long delay with the answer) - changing linux elevator changes almost nothing in the results - modulo some random "fluctuations". In any case, NCQ - at least in this drive - just does not work. Linux with its I/O elevator may help to speed things up a bit, but the disk does nothing in this area. NCQ doesn't slow things down either - it just does not work. The same's for ST3250620NS "enterprise" drives. By the way, Seagate announced Barracuda ES 2 series (in range 500..1200Gb if memory serves) - maybe with those, NCQ will work better? Or maybe it's libata which does not implement NCQ "properly"? (As I shown before, with almost all ol'good SCSI drives TCQ helps alot - up to 2x the difference and more - with multiple I/O threads) /mjt - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
