[stgt] tgt-admin and a -C, --control-port argument

Steven Wertheimer swerthei at gmail.com
Tue Apr 6 16:18:46 CEST 2010

Hello. Please pardon this post from someone new to the list if this
is irrelevant, but I've recently been involved in setting up iscsi on
a performance testing cluster, and I have observed that a single
tgtd process does seem to be a bottleneck in a high-throughput
(10GbE) environment, and that performance improves when I
use multiple tgtd processes.

If you want the details about this configuration, please let me know.



On 2010-04-05 22:48, FUJITA Tomonori wrote:
> On Tue, 6 Apr 2010 15:35:25 +1000
> ronnie sahlberg<ronniesahlberg at gmail.com>  wrote:
>> I dont think that is viable for Chandra.
>> TGTD is pretty limited performance wise with its central eventloop. On
>> a many-core machine with a lot of memory
>> the central event loop quickly becomes a bottleneck.
> Can you have the performance analysis with tools such as perf?
> The most of network processing happens in kernel space. The I/O
> processing too. They are not related with the number of user
> processes.
> Yeah, tgtd would be a bottleneck but there are lots of other possible
> bottlenecks.
>> For these usecases you really want to run multiple instances of tgtd.
>> In particular if you have a high-end storage subsystem attached
>> that can deliver high enough throughput.
>> Perhaps have one instance of TGTD for each 10GbE adapter. Perhaps one
>> instance of TGTD for every 2 cores.
> As I said yesterday, I think that we need to think about using
> multiple threads for targets (or initiators) if necessary. But we need
> the evidence first.
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