FUJITA Tomonori wrote: > On Thu, 17 Jan 2008 12:48:28 +0300 > Vladislav Bolkhovitin <vst@xxxxxxxx> wrote: > > >> FUJITA Tomonori wrote: >> >>> On Thu, 17 Jan 2008 10:27:08 +0100 >>> "Bart Van Assche" <bart.vanassche@xxxxxxxxx> wrote: >>> >>> >>> >>>> Hello, >>>> >>>> I have performed a test to compare the performance of SCST and STGT. >>>> Apparently the SCST target implementation performed far better than >>>> the STGT target implementation. This makes me wonder whether this is >>>> due to the design of SCST or whether STGT's performance can be >>>> improved to the level of SCST ? >>>> >>>> Test performed: read 2 GB of data in blocks of 1 MB from a target (hot >>>> cache -- no disk reads were performed, all reads were from the cache). >>>> Test command: time dd if=/dev/sde of=/dev/null bs=1M count=2000 >>>> >>>> STGT read SCST read >>>> performance (MB/s) performance (MB/s) >>>> Ethernet (1 Gb/s network) 77 89 >>>> IPoIB (8 Gb/s network) 82 229 >>>> SRP (8 Gb/s network) N/A 600 >>>> iSER (8 Gb/s network) 80 N/A >>>> >>>> These results show that SCST uses the InfiniBand network very well >>>> (effectivity of about 88% via SRP), but that the current STGT version >>>> is unable to transfer data faster than 82 MB/s. Does this mean that >>>> there is a severe bottleneck present in the current STGT >>>> implementation ? >>>> >>> I don't know about the details but Pete said that he can achieve more >>> than 900MB/s read performance with tgt iSER target using ramdisk. >>> >>> http://www.mail-archive.com/stgt-devel@xxxxxxxxxxxxxxxx/msg00004.html >>> >> Please don't confuse multithreaded latency insensitive workload with >> single threaded, hence latency sensitive one. >> > > Seems that he can get good performance with single threaded workload: > > http://www.osc.edu/~pw/papers/wyckoff-iser-snapi07-talk.pdf > > > But I don't know about the details so let's wait for Pete to comment > on this. > > Perhaps Voltaire people could comment on the tgt iSER performances. > We didn't run any real performance test with tgt, so I don't have numbers yet. I know that Pete got ~900 MB/sec by hacking sgp_dd, so all data was read/written to the same block (so it was all done in the cache). Pete - am I right? As already mentioned, he got that with IB SDR cards that are 10 Gb/sec cards in theory (actual speed is ~900 MB/sec). With DDR cards (20 Gb/sec), you can get even more. I plan to test that in the near future. Erez - 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
