On Thu, Jan 24, 2008 at 11:36:45AM +0100, Bart Van Assche wrote: >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 >> >> buffered i/o lmdd >> write/read 682/438 MB/s >> lmdd if=internal of=/dev/sdc bs=1M count=5000 >> lmdd of=internal if=/dev/sdc bs=1M count=5000 >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 ... and 1.1GB/s writes :) presumably because buffer aggregation works well. >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" >... the direct i/o read speed being twice the buffered i/o speed would seem to imply that Linux's page cache is being slow and confused with this particular set of kernel + OS + OFED versions. I doubt that this result actually says that much about tgt really. >Regarding write performance: the write tests were performed with a >real target (three disks in RAID-0, write bandwidth about 100 MB/s). I I'd be interested to see ramdisk writes. cheers, robin - 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
