[openib-general] question on QoS support

[Sasha Khapyorsky]

On 17:42 Wed 01 Nov     , Makia Minich wrote:
> 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,

AFAIK there is option -Q which enables/disables QoS configuration, it
does nothing with particular qos_high_limit parameter. Configuration
parameters (qos_max_vls, qos_high_limit, qos_vlarb_high, qos_vlarb_low
and qos_sl2vl templates) should be specified in opensm.opts file (or
other OpenSM configuration file which does not exist yet).

> 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?

Yes, you need to specify QoS parameters in opensm.opts file.

There is some readme file osm/doc/qos-config.txt which describes
details (I think man page have similar section too).


Ah, important note with OFED QoS is disabled by default in OpenSM, so -Q
option should be used, which for OFED means --qos. OpenSM from trunk
supports QoS configuration by default and -Q option disables this (and
means --no-qos), this can be confused, I know.

Sasha


> 
> 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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> >>
> > 
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> > 
> 
> -- 
> Makia Minich <minich at ornl.gov>
> National Center for Computation Science
> Oak Ridge National Laboratory
> Phone: 865.574.7460