On Jan 24, 2008 8:06 AM, Robin Humble <robin.humble+stgt@xxxxxxxxxx> wrote: > On Tue, Jan 22, 2008 at 01:32:08PM +0100, Bart Van Assche wrote: > > > >............................................................................................. > >. . STGT read SCST read . STGT read SCST read . > >. . performance performance . performance performance . > >. . (0.5K, MB/s) (0.5K, MB/s) . (1 MB >MB/s) (1 MB, MB/s) . > >............................................................................................. > >. Ethernet (1 Gb/s network) . 77 78 . 77 89 . > >. IPoIB (8 Gb/s network) . 163 185 . 201 239 . > >. iSER (8 Gb/s network) . 250 N/A . 360 N/A . > >. SRP (8 Gb/s network) . N/A 421 . N/A 683 . > >............................................................................................ > > how are write speeds with SCST SRP? > for some kernels and tests tgt writes at >2x the read speed. > > also I see much higher speeds that what you report in my DDR 4x IB tgt > testing... which could be taken as inferring that tgt is scaling quite > nicely on the faster fabric? > ib_write_bw of 1473 MB/s > ib_read_bw of 1378 MB/s > > iSER to 7G ramfs, x86_64, centos4.6, 2.6.22 kernels, git tgtd, > initiator end booted with mem=512M, target with 8G ram > > direct i/o dd > write/read 800/751 MB/s > dd if=/dev/zero of=/dev/sdc bs=1M count=5000 oflag=direct > dd of=/dev/null if=/dev/sdc bs=1M count=5000 iflag=direct > > buffered i/o dd > write/read 1109/350 MB/s > dd if=/dev/zero of=/dev/sdc bs=1M count=5000 > dd of=/dev/null if=/dev/sdc bs=1M count=5000 Hello Robin, The tests I performed were read performance tests with dd and with buffered I/O. For this test you obtained 350 MB/s with STGT on a DDR 4x InfiniBand network, while I obtained 360 MB/s on a SDR 4x InfiniBand network. I don't think that we can call this "scaling up" ... Regarding write performance: the write tests were performed with a real target (three disks in RAID-0, write bandwidth about 100 MB/s). I did not yet publish these numbers because it is not yet clear to me how much disk writing speed / InfiniBand transfer speed / target write buffering each contribute in the results. The results I obtained in the write tests (dd, buffered I/O) show the same trend as for the read tests: for large data transfers over a Gigabit Ethernet network the results for STGT and SCST are similar. For small transfer sizes (512 bytes) or fast network technology (SRP / iSER) the write performance of SCST is significantly better than that of STGT. Bart. Bart. - 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
