QDIO inbound workload queueing

OSA-Express3 or later features can perform a degree of traffic sorting by placing inbound packets for differing workload types on separate processing queues. This function is called QDIO inbound workload queueing (IWQ). With the inbound traffic stream already sorted by the OSA-Express feature, z/OS® Communications Server provides the following performance optimizations:

Finer tuning of read-side interrupt frequency to match the latency demands of the various workloads that are serviced
Improved multiprocessor scalability, because the multiple OSA-Express input queues are now efficiently serviced in parallel

When QDIO IWQ is enabled, z/OS Communications Server and the OSA-Express feature establish a primary input queue and one or more ancillary input queues (AIQs), each with a unique read queue identifier (QID) for inbound traffic. z/OS Communications Server and the OSA-Express feature cooperatively use the multiple queues in the following way:

The OSA-Express feature directs an inbound packet (received on this interface) that is to be forwarded by the sysplex distributor to the sysplex distributor AIQ. z/OS Communications Server then tailors its processing for the sysplex distributor queue, notably by using the multiprocessor to service sysplex distributor traffic in parallel with traffic on the other queues.
The TCP layer automatically detects connections operating in a bulk-data fashion (such as the FTP data connection), and these connections are registered to the receiving OSA-Express feature as bulk-mode connections. The OSA-Express feature then directs an inbound packet (received on this interface) for any registered bulk-mode connection to the TCP bulk-data AIQ. z/OS Communications Server tailors its processing for the bulk queue, notably by improving in-order packet delivery on multiprocessors, which likely results in improvements to CPU consumption and throughput. Like other AIQs, processing for data on the bulk queue can be in parallel with traffic on the other queues.
The OSA-Express feature directs an inbound Enterprise Extender packet (received on this interface) to the Enterprise Extender AIQ. This allows z/OS Communications Server to process inbound traffic on the Enterprise Extender queue in parallel with inbound traffic on the other queues for this interface.
If a packet is not directed to an AIQ, the OSA-Express feature directs the packet to the primary input queue.

Requirement: QDIO IWQ is limited to OSA-Express3 or later Ethernet features in QDIO mode that are running on an IBM® System z10™ GA3 or later server. For more information, see the 2097DEVICE, 2098DEVICE, or 2817DEVICE Preventive Service Planning (PSP) buckets as appropriate.

Restrictions:

QDIO IWQ is not supported for IPAQENET interfaces defined with the DEVICE, LINK, and HOME statements. You must convert your IPAQENET definitions to use the INTERFACE statement to enable this support. For more information, see Steps for converting from IPv4 IPAQENET DEVICE, LINK, and HOME definitions to the IPv4 IPAQENET INTERFACE statement.
QDIO IWQ is not supported for a z/OS guest on z/VM® using simulated (virtual) devices, such as virtual switch (VSWITCH) or guest LAN.
Bulk-mode TCP connection registration is supported only in configurations in which a single inbound interface is servicing the bulk-mode TCP connection. If a bulk-mode TCP connection detects that it is receiving data over multiple interfaces, QDIO IWQ is disabled for the TCP connection and inbound data from that point forward is delivered to the primary input queue.
QDIO IWQ does not apply for traffic that is sent over an OSA port that is shared by the receiving TCP/IP stack when an indirect route (where the next hop and destination IP address are different) is being used; this traffic is placed on the primary input queue. QDIO IWQ does apply when traffic on the shared OSA path uses a direct route (where the next hop and destination IP address are the same).

Guideline: Display the VTAM® TRLE name that is associated with the interface to determine the amount of CSM storage that is being used. Additional CSM 4K DSPACE64 storage is used when the QDIO inbound workload queue is implemented.