On Fri, 2011-12-16 at 22:57 +0800, Asias He wrote:
> On 12/15/2011 08:15 PM, Sasha Levin wrote:
> > When using AIO, submit all requests which exists in the vring in a
> single
> > io_submit instead of one io_submit for each descriptor.
> >
> > Benchmarks:
> >
> > Short version: 15%+ increase in IOPS, small increase in BW.
> >
> > Read IOPS:
> > Before:
> > vda: ios=291792/0, merge=0/0, ticks=35229/0, in_queue=31025,
> util=61.30%
>
> I guess you are reading the wrong IOPS number, the 'ios' is the number
> of ios performed by all groups, not the IOPS result. Find the
> 'iops' ;-)
>
> So, Here is the number without/with this patch.
>
> (seq-read, seq-write, rand-read, rand-write)
>
> Before:
> read : io=98304KB, bw=63015KB/s, iops=15753, runt= 1560msec
> write: io=98304KB, bw=56823KB/s, iops=14205, runt= 1730msec
> read : io=98304KB, bw=62139KB/s, iops=15534, runt= 1582msec
> write: io=98304KB, bw=53836KB/s, iops=13458, runt= 1826msec
>
> After:
> read : io=98304KB, bw=63096KB/s, iops=15774, runt= 1558msec
> write: io=98304KB, bw=55823KB/s, iops=13955, runt= 1761msec
> read : io=98304KB, bw=59148KB/s, iops=14787, runt= 1662msec
> write: io=98304KB, bw=55072KB/s, iops=13768, runt= 1785msec
>
> Submit more io requests in one time is not supposed to increase the
> iops
> or bw so dramatically.
>
> I even tried to submit all read/write ops in one io_submit which still
> ends up with very little iops or bw improvement.
Did you test it vs /dev/shm?
These are the results I see from the same test:
Before:
read : io=1157.7MB, bw=118110KB/s, iops=29527 , runt= 10037msec
write: io=1083.6MB, bw=110867KB/s, iops=27716 , runt= 10008msec
After:
read : io=1304.4MB, bw=133337KB/s, iops=33334 , runt= 10017msec
write: io=1292.4MB, bw=132087KB/s, iops=33021 , runt= 10019msec
--
Sasha.
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