[Stgt-devel] [Iscsitarget-devel] call for testers for tgt

[Tomasz Chmielewski]

FUJITA Tomonori schrieb:
> From: Tomasz Chmielewski <mangoo at wpkg.org>
> Subject: Re: [Iscsitarget-devel] call for testers for tgt
> Date: Thu, 03 May 2007 12:40:13 +0200
> 
>> FUJITA Tomonori schrieb:
>>> I'm looking for testers for tgt iSCSI target code.
>>>
>>> tgt has been developed to replace IET, as mentioned several times on
>>> this mailing list.
>>>
>>> The iSCSI target code runs in user space. So you have no kernel
>>> crashes unlike IET and it's easy to compile the source code.
>> What performance can we expect? Same as IET? Worse?
> 
> Should be comparable.
> 
> At least, sg_turs gave the comparable results (you can find more in
> the stgt-devel mailing list):
> 
> 
>>> paris:~# sg_turs -t -n=1000 /dev/sg3
>>> time to perform commands was 0.125131 secs; 7991.62 operations/sec
>>> Completed 1000 Test Unit Ready commands with 0 errors
>>>
>>> - IET
>>>
>>> paris:~# sg_turs -t -n=1000 /dev/sg3
>>> time to perform commands was 0.128747 secs; 7767.17 operations/sec
>>> Completed 1000 Test Unit Ready commands with 0 errors
> 
> IET uses the user-space APIs in the kernel-space. It doesn't try
> to use the optimal in-kernel APIs. open-iscsi does (e.g. performing
> PDUs in	RX_SOFTIRQ) so the networking code is more complex.
> 
> Unless you use 10Gbit, I don't think you need to worry about the
> performance. Let me know if you find the performance difference.

I made a very simple test using "dd":

Target - native HDD speed

# dd if=nagios-swap of=/dev/null
1024000+0 records in
1024000+0 records out
524288000 bytes (524 MB) copied, 8.03441 seconds, 65.3 MB/s


IET 0.4.15:

# dd if=part of=/dev/null
1024000+0 records in
1024000+0 records out
524288000 bytes (524 MB) copied, 12,0278 seconds, 43,6 MB/s


tgtd 20070503:

# dd if=part of=/dev/null
1024000+0 records in
1024000+0 records out
524288000 bytes (524 MB) copied, 22,8263 seconds, 23,0 MB/s


Each test was performed three times, and gave similar results (~0,3 MB 
difference can be discarded).


Tests were carried over 1 Gb link.

Target is running: 600 MHz Celeron M CPU with 256 MB RAM.

Initiator is running: 3.20 Ghz Pentium 4 CPU, with 3 GB RAM.


Neither the target nor initiator were performing any other tasks when 
the tests were made.


-- 
Tomasz Chmielewski
http://wpkg.org