[Stgt-devel] Different throughput numbers on SLES 10 and RHEL 5.1

Mike Christie michaelc
Thu Feb 28 15:30:09 CET 2008

Erez Zilber wrote:
> Hi,
> I'm using the latest stgt release (tgt-20071227) and I see different
> throughput numbers for READ commands on SLES 10  & RHEL 5.1. I'm using
> stgt with iSCSI over iSER.
> I'm using the same initiator (open-iscsi 865.15 from OFED 1.3 rc4) and
> the same target machine. The target machine has 2 partitions - one is
> SLES 10 & the other is RHEL 5.1. When I run READ commands against the
> target on SLES 10, I get ~400 MB/sec (which is the throughput of the
> LUN). When I run the same READ commands from the same initiator against
> the target on RHEL 5.1, I get only 240 MB/sec.
> Is there anything that I need to config on the RHEL 5.1 machine? BTW -
> if I run the same test directly from the target machine, I get 400
> MB/sec on both distros.
> Here's the command that I use:
> sgp_dd if=/dev/sdc of=/dev/null bs=512 bpt=1024 thr=8 time=1 count=20480000

Does this command try to keep 8 IOs running in parrallel, and if so did 
you try the noop scheduler (I think for SG_IO this will not make a 

Is the target by any chance running on a x86_64 box?

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