Re: [patch 2/3 v3] raid1: read balance chooses idlest disk for SSD

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 [off-list ref]:

On Sun, Jul 01, 2012 at 11:13:42PM -0300, Roberto Spadim wrote:

quoted

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
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Roberto Spadim
Spadim Technology / SPAEmpresarial