On Wed, 2012-06-13 at 18:13 +0800, mengcong wrote: > Hi folks, I did an IO performance test on the tcm-vhost scsi. I want to share > the test result data here. > > > seq-read seq-write rand-read rand-write > 8k 256k 8k 256k 8k 256k 8k 256k > ---------------------------------------------------------------------------- > bare-metal 67951 69802 67064 67075 1758 29284 1969 26360 > tcm-vhost-iblock 61501 66575 51775 67872 1011 22533 1851 28216 > tcm-vhost-pscsi 66479 68191 50873 67547 1008 22523 1818 28304 > virtio-blk 26284 66737 23373 65735 1724 28962 1805 27774 > scsi-disk 36013 60289 46222 62527 1663 12992 1804 27670 > > unit: KB/s > seq-read/write = sequential read/write > rand-read/write = random read/write > 8k,256k are blocksize of the IO > > In tcm-vhost-iblock test, the emulate_write_cache attr was enabled. > In virtio-blk test, cache=none,aio=native were set. > In scsi-disk test, cache=none,aio=native were set, and LSI HBA was used. > > I also tried to do the test with a scsi-generic LUN (pass through the > physical partition /dev/sgX device). But I couldn't setup it > successfully. It's a pity. > > Benchmark tool: fio, with ioengine=aio,direct=1,iodepth=8 set for all tests. > kvm vm: 2 cpus and 2G ram > These initial performance results look quite promising for virtio-scsi. I'd be really interested to see how a raw flash block device backend that locally can do ~100K 4k mixed R/W random IOPs compares with virtio-scsi guest performance as the random small block fio workload increases.. Also note there is a bottleneck wrt to random small block I/O performance (per LUN) on the Linux/SCSI initiator side that is effecting things here. We've run into this limitation numerous times with using SCSI LLDs as backend TCM devices, and I usually recommend using iblock export with raw block flash backends for achieving the best small block random I/O performance results. A number of high performance flash storage folks do something similar with raw block access (Jen's CC'ed) As per Stefan's earlier question, how does virtio-scsi to QEMU SCSI userspace compare with these results..? Is there a reason why these where not included in the initial results..? Thanks Meng! --nab -- 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
