Bart Van Assche wrote: > On Jan 24, 2008 8:06 AM, Robin Humble <robin.humble+stgt at anu.edu.au> 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. Robin, There is a fundamental difference between regular dd-like reads and writes: reads are sync, i.e. latency sensitive, but writes are async, i.e. latency insensitive. You should use O_DIRECT dd writes for the fair comparison. Vlad |