[ewg] Re: [Scst-devel] SRP performance in SCST

[Bart Van Assche]

On Mon, Mar 10, 2008 at 3:20 PM, Doron Shoham <dorons at voltaire.com> wrote:
>  I used the following commands:
>  for write commands:
>  sgp_dd of=/dev/sg1 if=/dev/zero bs=512 bpt=<from 2-512> thr=8 time=1 count=20M
>  for read commands
>  sgp_dd if=/dev/sg1 of=/dev/null bs=512 bpt=<from 2-512> thr=8 time=1 count=20M
>
>  And the results are (all in MB/s):
>  bpt:            2       4       8       16      32      64      128     256     512
>  Write           22.5    41.4    80.6    160     275     443     570     740     810
>  Read            42      80      170     313     550     940     1200    1312    1300
>
>  What can be the reason for such difference between the bandwidth of Read and Write commands?

Can you please try to use direct I/O instead of buffered I/O ?

Bart.