Hi Vivek, On Wed, Dec 21, 2011 at 02:11:17PM -0500, Vivek Goyal wrote: > On Wed, Dec 21, 2011 at 10:00:48AM +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 > > May be using deadline or noop in guest is better to benchmark against > PCI-E based flash. Good suggestion. I tested it by deadline on guest side. The result is not good. Although gap is within noise, Batch BIO's random performance is regressed compared to CFQ. Request Batch BIO (MB/s) stddev (MB/s) stddev w 787.030 31.494 w 748.714 68.490 rw 216.044 29.734 rw 216.977 40.635 r 771.765 3.327 r 771.107 4.299 rr 280.096 25.135 rr 258.067 43.916 I did some small test for only Batch BIO with deadline and cfq. to see I/O scheduler's effect. I think result is very strange, deadline :149MB, CFQ : 87M Because Batio BIO patch uses make_request_fn instead of request_rfn. So I think we should not affect by I/O scheduler.(I mean we issue I/O before I/O scheduler handles it) What do you think about it? Do I miss something? 1) deadline [root@RHEL-6 ~]# ./aio-stress -c 1 -t 1 -s 128 -r 8 -O -o 3 -d 512 /dev/vda num_thread 1 adding stage random read starting with random read file size 128MB, record size 8KB, depth 512, ios per iteration 8 max io_submit 8, buffer alignment set to 4KB threads 1 files 1 contexts 1 context offset 2MB verification off Running single thread version random read on /dev/vda (149.40 MB/s) 128.00 MB in 0.86s thread 0 random read totals (149.22 MB/s) 128.00 MB in 0.86s 2) cfq [root@RHEL-6 ~]# ./aio-stress -c 1 -t 1 -s 128 -r 8 -O -o 3 -d 512 /dev/vda num_thread 1 adding stage random read starting with random read file size 128MB, record size 8KB, depth 512, ios per iteration 8 max io_submit 8, buffer alignment set to 4KB threads 1 files 1 contexts 1 context offset 2MB verification off Running single thread version random read on /dev/vda (87.21 MB/s) 128.00 MB in 1.47s thread 0 random read totals (87.15 MB/s) 128.00 MB in 1.47s > > Thanks > Vivek -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
