memreq Event Set

Available only on Itanium 9300 quad-core processor systems.

The memreq event set provides data about memory read latency and cacheable and uncacheable memory requests.

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:

•Read Rate

Number of memory read requests per second.

•Live Reads

This is the average number of outstanding reads per cycle. This gives some idea about the memory request density.

•Ave Latency - Cycle

Average system memory read latency in CPU cycles.

•Ave Latency - Nsec

Average system memory read latency in nanoseconds.

•Pftch

This is total number of cacheable instruction prefetch memory requests per 1000 retired instructions, including nops and predicated off instructions.

•Dmnd

This is total number of cacheable instruction demand fetch memory requests per 1000 retired instructions, including nops and predicated off instructions.

•Load

This is total number of cacheable loads per 1000 retired instructions, including nops and predicated off instructions.

•Store

This is total number of cacheable RFO (Read For Ownership) stores per 1000 retired instructions, including nops and predicated off instructions.

•Hint

This is total number of cacheable RFO (Read For Ownership) hints per 1000 retired instructions, including nops and predicated off instructions.

•WB - 128

This is total number of cacheable 128-byte write backs per 1000 retired instructions, including nops and predicated off instructions.

242 Event Set Descriptions for CPU Metrics