[openib-general] question on QoS support

[Makia Minich]

It just so happens that we've started looking at this here at ORNL as
well.  I had a question about the options.  The manpage makes it seem
that you can set these qos options (e.g. qos_high_limit) from the
command line, but I haven't been overly successful.  Is there an example
of this being done?  Or is changing the /var/cache/osm/opensm.opts file
the preferred method of changing the options?

Sasha Khapyorsky wrote:
> On 16:52 Wed 01 Nov     , Oliver wrote:
>> Hi, folks -
>>
>> I am trying to verify and evaluate IB QoS support, running openSM as
>> subnet manager. The perftest program is extended to set SL as command
>> line options instead of default 0, and by modifying VL arbitration
>> tables, I am expecting to see the traffic shaping can actually take
>> place, but it did not.  More details on configuration:
>>
>> in opensm.opts:
>> # QoS default options
>> qos_high_limit 255 # disable low priority table
>> qos_vlarb_high: 0:4,1:4,2:8,3:0, 4:0 .... # this is to give VL 2
>> (corresponding to SL 2) a higher weight 8
>> qos_sl2vl 0,1,2,3,4, ... # no changes here
>>
>> I think (though not verified) the Voltaire HCA we are using can
>> support 8 data VLs. I don't have much more information to go on why
>> qos shaping is not taking place, any suggestions?
> 
> You can verify actual port's parameters with smpquery (from diags), you
> will need to run to get QoS related parameters:
> 
>   smpquery portinfo ...
>   smpquery vlarb ...
>   smpquery sl2vl ...
> 
> Sasha
> 
>> A related question is, if I modify qos setting in SM, do I need to
>> restart SA on each hosts for it to see the changes? (I am hoping not,
>> as I tried in the test, it doesn't seem to make a difference)
>>
>> Thanks for help.
>> -- 
>> Oliver
>>
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-- 
Makia Minich <minich at ornl.gov>
National Center for Computation Science
Oak Ridge National Laboratory
Phone: 865.574.7460