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

[Erez Zilber]

Mike Christie wrote:
> 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
> difference)?

I tried noop & cfq, but didn't see any dramatic change. BTW -
if=/dev/sg3 (not /dev/sdc), so the command that I'm running is:

sgp_dd if=/dev/sg3 of=/dev/null bs=512 bpt=1024 thr=8 time=1 count=20480000

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

Yes. Which box are you using? BTW - our non-stgt target is also running
on a x86_64 box successfully.

Erez