[Stgt-devel] Tuning iSER for performance

Erez Zilber erezz
Tue Feb 12 11:06:43 CET 2008

Bart Van Assche wrote:
> On Feb 11, 2008 6:59 AM, Erez Zilber <erezz at voltaire.com> wrote:
>> I'm not talking about running the initiator & the target from the same
>> machine. What I said is that if you're running the initiator on machine
>> 'A' and the target on machine 'B', I see the following behavior:
>>     * running sgp_dd directly from the target machine - 400 MB/sec
>>       (which is the throughput of the LUN)
>>     * running sgp_dd from the initiator on the same LUN - 240 MB/sec
>> If you get better numbers, I'm interested to know if you're using the
>> default config or anything else.
> The results I obtained with STGT over iSER on an SDR network are as
> follows (direct I/O with  xdd):
> * 7.4 MB/s for reading data in blocks of 512 bytes and 8.9 MB/s for writing.
> * 363 MB/s for reading data in blocks of 65536 bytes and 346 MB/s for writing.
> * 890 MB/s for reading data in blocks of 10 MB and 900 MB/s for writing.
> Please keep in mind that when running a filesystem on top of iSCSI
> that all transfers happen in units of 64 KB or less.
> Bart Van Assche.

Can you send more details about your configuration?

    * stgt version
    * initiator version
    * Which distro do you use for the initiator/target?
    * Which benchmark do you use? What are the parameters?
    * What are the results if you run the same benchmark directly from
      the target machine (i.e. no iSCSI & iSER involved)?
    * Are you using the default config for the initiator/target?

Here's my config:

    * target:

            tgt-20071227 (actually, I use the RPM that I uploaded to OpenFabrics, which is almost identical to tgt-20071227)

          o SLES 10
          o default stgt config
    * initiator:
          o OFED 1.3 rc4
          o SLES 10 sp1
          o default open-iscsi config

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