HP Caliper User's Guide

queues Event Set
Available only on Itanium 2 and dual-core Itanium 2 systems.
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[:all|user|kernel]
• 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
336 Event Set Descriptions for CPU Metrics