[openib-general] Srp question

[Vu Pham]

> 
> By default, we found (via stats from the DDN) that we were only seeing reads
> and writes in the 0-32Kbyte range.  Comparing IBGold and OFED, we found that
> the srp_sg_tablesize defaulted to 256, but in OFED it defaulted to 12.  So,
> changing this (via modprobe.conf) to 256 in OFED, we were able to see reads
> and writes in the 128Kbyte range (which is what ultimately got us to the
> performance above).  I also noticed that there is a max_sects option you can
> pass to add_target (in the SRP /sys entries) which seemed to be the same
> idea as srp_sg_tablesize, but this didn't seem to affect anything.
> 
> So, my question is, what is the right magic to get SRP up to speed?


I played around with these parameters: srp_sg_tablesize (via 
modprobe.conf or passing it directly), max_sect and 
max_cmd_per_lun.

srp_sg_tablesize={32, 64, and 128}
max_sect={512, 1024, and 2048}
max_cmd_per_lun={1, 2, 4, 8, 16, 32, and default 64} --> 
this really depends on the storage to have the right number

-vu