[ofa-general] [PATCH 3/3] IB/srp: use scatter gather chaining

[Dillow, David A.]

>From Roland Drier:
 > I looked through the DMA paths on the hardware drivers to ensure they
 > could take advantage of the SG chaining, and it seems that every one
 > except iPath uses the system's DMA routines, which have been converted
 > to handle chaining. iPath looks like it should be OK, but I have no way
 > to test it.

set srp_sg_tablesize=256
Add SRP target with max_sects=8192 or more

echo 4096 > /sys/block/sda/queue/max_sectors_kb
echo noop > /sys/block/sda/queue/scheduler

dd if=/dev/zero of=/dev/sda oflag=direct bs=4096k count=10
dd if=/dev/sda iflag=direct of=/dev/sda bs=4096k count=10

You may not get 4MB I/Os because of memory fragmentation, but you should see 1MB
or better. You can use a real file as a data source/sink to verify against
corruption.

Dave