[ofa-general] OpenSM QoS Query

[Amar Mudrankit]

Considering the following QoS configuration for OpenSM running over OFED-1.3.1


 /var/cache/opensm/opensm.opts

# QoS default options
qos_max_vls 8
qos_high_limit 8
qos_vlarb_high 1:1,2:1
qos_vlarb_low 1:1
qos_sl2vl 0,1,2,3,4,5,6,7,15,15,15,15,15,15,15,15


/etc/opensm/qos-policy.conf

qos-ulps

           default    :  0
           ipoib      :   1
           srp, target-port-guid <some-valid-port-guid>  : 2

end-qos-ulps

IPoIB running in connected mode with MTU of 65520 bytes.

In this scenario, do we expect SRP to starve and will not get an
opportunity to send data?

This is because, if the packet size of IPoIB data is 64K, the Limit of
High Priority(8 * 4KB) will be eaten up by IPoIB itself so that next
active table would be low priority VL arbitration table. In the low
priority VL arbitration table also, we have configured IPoIB, which
will send IPoIB data. Eventually when high priority table will become
active again, 64K ipoib data will be sent. This will not ever schedule
service level 2 (of that of SRP). Is this understanding correct?

or

When the second time High priority VL arbitration table becomes
active, the current pointer will be pointing to service level 2 in
high priority table and SRP data can flow? I am not sure if this
second possibility is valid.


Thanks and Regards,
Amar