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 .
............................................................................................
Results with /dev/ram0 configured as backing store on the target (buffered I/O):
Read Write Read Write
performance performance performance performance
(0.5K, MB/s) (0.5K, MB/s) (1 MB, MB/s) (1 MB, MB/s)
STGT + iSER 250 48 349 781
SCST + SRP 411 66 659 746
Ib_rdma_bw now reports 933 MB/s on the same system, correct? Those
~250MB/s difference is what you will gain with zero-copy IO implemented
and what STGT with the current architecture has no chance to achieve.
Results with /dev/ram0 configured as backing store on the target (direct I/O):
Read Write Read Write
performance performance performance performance
(0.5K, MB/s) (0.5K, MB/s) (1 MB, MB/s) (1 MB, MB/s)
STGT + iSER 7.9 9.8 589 647
SCST + SRP 12.3 9.7 811 794
Bart.
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