HP UX IPFilter Software manual Queues Event Set

The queues event set provides bus request queue (BRQ) information that might give insight into possible performance problems related to the system bus. The BRQ is a centralized queueing structure that collects almost all requests from the L1 cache and then schedules those requests to the L2 cache or front side bus (FSB). High values on the available metrics will likely indicate levels of bus utilization. This can be confirmed with the sysbus event set.

If you use this event set, the default is to make the measurements irrespective of CPU operating state (that is, user, system, or interrupt states). By default, the idle state is not included in the measurement. You can use command-line options to limit the scope of the measurement. Specifically, you can:

•Limit measurement to a specific privilege level: -m event_set[:alluserkernel]

•Include idle: --exclude-idle False

•Exclude the interruption state: --measure-on-interrupts off

•Only measure the interruption state: --measure-on-interrupts only

Metrics Available from this Measurement

The following metrics are available from this event set. These descriptions do not take into account any command-line options you might use.

The metrics are:

•CPU Cycles

This is the number of CPU cycles that were observed during the sample period. It is used with BRQ read requests issued to compute the BRQ requests insert rate. It can also be useful to determine the percentage of time it is being monitored.

•BRQ Read Requests Inserted

•This is a count of the number of requests that were inserted into the BRQ during the sample observation period.

•BRQ Read Requests Per Sec

This is the number of BRQ requests inserted per second. It gives a view of the total demand that a processor is delivering to the system.

•AVG BRQ Live Entries Per Cycle (not present in dual-core Itanium 2 and Itanium 9300 quad-core processor systems)

This is the average number live BRQ entries on a per-cycle basis. You can use it to obtain an idea of how the system is responding to load. Values less than 1.0 indicate very light load, and values approaching the depth of the BRQ queue (16) indicate a system under considerable stress.

•AVG BRQ Latency

This is the average number of cycles that a request resides in the BRQ. It is also useful for interpreting system loading. Large values (> 20 cycles) indicate that the processor is being delayed during bus request arbitration, probably due to excessive bus utilization by a priority agent (I/O).

•AVG IOQ Live Entries Per Cycle

The in-order queue (IOQ) monitors all outstanding bus transactions generated by any bus agent. Requests are loaded into the IOQ during the bus transaction request phase. Transactions are retired from the IOQ on receipt of a positive response status from the bus. This metric provides an estimate of the number of bus transactions that are live in the IOQ on a per-cycle basis. A high value for this metric would be indicative of high system bus utilization (many transactions in flight).

•AVG OOQ Live Entries Per Cycle

If a deferred response is received while a request is live in the IOQ, it is moved to the out-of-order queue (OOQ). When the response for the deferred transaction is received, the OOQ entry is moved to the end of the IOQ to complete the processing of the transaction. This

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