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.
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