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SubjectRe: [PATCH 0/6][RFC] virtio-blk: Change I/O path from request to BIO
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On Wed, 2011-12-21 at 10:00 +0900, Minchan Kim wrote:
> This patch is follow-up of Christohp Hellwig's work
> [RFC: ->make_request support for virtio-blk].
> http://thread.gmane.org/gmane.linux.kernel/1199763
>
> Quote from hch
> "This patchset allows the virtio-blk driver to support much higher IOP
> rates which can be driven out of modern PCI-e flash devices. At this
> point it really is just a RFC due to various issues."
>
> I fixed race bug and add batch I/O for enhancing sequential I/O,
> FLUSH/FUA emulation.
>
> I tested this patch on fusion I/O device by aio-stress.
> Result is following as.
>
> Benchmark : aio-stress (64 thread, test file size 512M, 8K io per IO, O_DIRECT write)
> Environment: 8 socket - 8 core, 2533.372Hz, Fusion IO 320G storage
> Test repeated by 20 times
> Guest I/O scheduler : CFQ
> Host I/O scheduler : NOOP
>
> Request BIO(patch 1-4) BIO-batch(patch 1-6)
> (MB/s) stddev (MB/s) stddev (MB/s) stddev
> w 737.820 4.063 613.735 31.605 730.288 24.854
> rw 208.754 20.450 314.630 37.352 317.831 41.719
> r 770.974 2.340 347.483 51.370 750.324 8.280
> rr 250.391 16.910 350.053 29.986 325.976 24.846
>
> This patch enhances ramdom I/O performance compared to request-based I/O path.
> It's still RFC so welcome to any comment and review.

I did a benchmark against a /dev/shm device instead of an actual storage
to get rid of any artifacts which are caused by the storage itself, and
saw that while there was a nice improvement across the board, the hit
against sequential read and write was quite significant.

I ran the tests with fio running in KVM tool against a 2G file located
in /dev/shm. Here is a summary of the results:

Before:
write_iops_seq
write: io=1409.8MB, bw=144217KB/s, iops=36054 , runt= 10010msec
write_bw_seq
write: io=7700.0MB, bw=1323.5MB/s, iops=1323 , runt= 5818msec
read_iops_seq
read : io=1453.7MB, bw=148672KB/s, iops=37168 , runt= 10012msec
read_bw_seq
read : io=7700.0MB, bw=1882.7MB/s, iops=1882 , runt= 4090msec
write_iops_rand
write: io=1266.4MB, bw=129479KB/s, iops=32369 , runt= 10015msec
write_bw_rand
write: io=7539.0MB, bw=1106.1MB/s, iops=1106 , runt= 6811msec
read_iops_rand
read : io=1373.3MB, bw=140475KB/s, iops=35118 , runt= 10010msec
read_bw_rand
read : io=7539.0MB, bw=1314.4MB/s, iops=1314 , runt= 5736msec
readwrite_iops_seq
read : io=726172KB, bw=72292KB/s, iops=18072 , runt= 10045msec
write: io=726460KB, bw=72321KB/s, iops=18080 , runt= 10045msec
readwrite_bw_seq
read : io=3856.0MB, bw=779574KB/s, iops=761 , runt= 5065msec
write: io=3844.0MB, bw=777148KB/s, iops=758 , runt= 5065msec
readwrite_iops_rand
read : io=701780KB, bw=70094KB/s, iops=17523 , runt= 10012msec
write: io=706120KB, bw=70527KB/s, iops=17631 , runt= 10012msec
readwrite_bw_rand
read : io=3705.0MB, bw=601446KB/s, iops=587 , runt= 6308msec
write: io=3834.0MB, bw=622387KB/s, iops=607 , runt= 6308msec

After:
write_iops_seq
write: io=1591.4MB, bw=162626KB/s, iops=40656 , runt= 10020msec
write_bw_seq
write: io=7700.0MB, bw=1276.4MB/s, iops=1276 , runt= 6033msec
read_iops_seq
read : io=1615.7MB, bw=164680KB/s, iops=41170 , runt= 10046msec
read_bw_seq
read : io=7700.0MB, bw=1407.1MB/s, iops=1407 , runt= 5469msec
write_iops_rand
write: io=1243.1MB, bw=126304KB/s, iops=31575 , runt= 10085msec
write_bw_rand
write: io=7539.0MB, bw=1206.3MB/s, iops=1206 , runt= 6250msec
read_iops_rand
read : io=1533.1MB, bw=156795KB/s, iops=39198 , runt= 10018msec
read_bw_rand
read : io=7539.0MB, bw=1413.7MB/s, iops=1413 , runt= 5333msec
readwrite_iops_seq
read : io=819124KB, bw=81790KB/s, iops=20447 , runt= 10015msec
write: io=823136KB, bw=82190KB/s, iops=20547 , runt= 10015msec
readwrite_bw_seq
read : io=3913.0MB, bw=704946KB/s, iops=688 , runt= 5684msec
write: io=3787.0MB, bw=682246KB/s, iops=666 , runt= 5684msec
readwrite_iops_rand
read : io=802148KB, bw=80159KB/s, iops=20039 , runt= 10007msec
write: io=801192KB, bw=80063KB/s, iops=20015 , runt= 10007msec
readwrite_bw_rand
read : io=3731.0MB, bw=677762KB/s, iops=661 , runt= 5637msec
write: io=3808.0MB, bw=691750KB/s, iops=675 , runt= 5637msec

--

Sasha.




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