Richard Frank <[EMAIL PROTECTED]> wrote: Richard> Are there any mechanisms available to the client process to manage the Richard> QoS level for the various supported ULPs (SDP,TCP,UDP,RDS,SRP,iSER,etc) Richard> either at the ULP level or some combination of process and ULP - or Richard> perhaps even at the connection level ?
To manage QoS the question is who knows about all the traffic traversing a specific adapter. For most kernel traversing protocols (IP, iSER, iSCSI, etc) you can sometimes do this in the device driver, where you can examine the headers as a packet is expedited and manage it there. Unfortunately you are adding processing in the driver which can end up impacting bandwidth on high speed adapters. You also introduce additional overhead hence higher CPU utilization. You can also introduce that in the adapter but I am not sure if the IB HCA spec has this capability defined. Richard> Using the same example, the cluster node monitors might set the Richard> priority / QoS level of the heart beats to be more important than normal Richard> SRP/iSER traffic to ensure no starvation ? When you add user space protocols such as SDP and MPI, then all bets are off. The kernel has no knowledge of the traffic from the users so can't properly manage QoS across all protocols. The user space traffic can mess up the kernel traversing protocols QoS calculations. The only place to handle QoS if user space protocols are used is in the adapter. Some switches can handle QoS once the traffic gets there but can't help the adapters in the nodes. Bernie King-Smith IBM Corporation Server Group Cluster System Performance [EMAIL PROTECTED] (845)433-8483 Tie. 293-8483 or wombat2 on NOTES "We are not responsible for the world we are born into, only for the world we leave when we die. So we have to accept what has gone before us and work to change the only thing we can, -- The Future." William Shatner _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
