The L2 instruction cache metrics include miss information for instruction prefetch requests and instruction demand requests.

There are a number of issues regarding L2 instruction cache access that need to be considered when interpreting L2 cache measurement results. The L2 cache will not count fetches to the second half of a line if the fetch for the first part is already counted. Secondary misses are counted as data references. Only requests that have entered the OZ queue are counted. And these instructions are not counted: FROM_CCV, SETF, PTC_G, FWB, MF, MFA, SYNCI, SYNCIA, PTCM, FC, and CC.

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

The event per kinst (event per 1000 instructions) metrics are computed using all instructions retired. This includes nops, predicated off instructions, failed speculation and instructions and associated recovery code as well as the architecturally visible instruction. You can eliminate idle loops effects by using the command-line option --exclude-idle True (which is the default). The effects of failed speculative operations and TLB misses cannot be directly eliminated, but you can get an estimate of the impact of events from the cspec, dspec, and tlb event sets. You can use the cpi event set to obtain the fraction of all instructions retired that have an architecturally visible result, except for predicated off branches, which are counted as useful instructions (non-taken branch) by the Itanium 2 PMU.

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:

•Total - Misses Per Second

This is the total number of L2 instruction cache misses per second. It includes all instruction prefetch misses and instruction demand fetch misses.

•Pfetch - Misses Per Second

This is the number of instruction line prefetch requests (streaming and non-streaming) that miss the L2 instruction cache per second.

•Dfetch - Misses Per Second

This is the number of instruction line demand requests that miss the L2 instruction cache per second.

•Total - Misses Per Kinst

This is the total number of L2 instruction cache misses per 1000 retired instructions, including nops and predicated off instructions. It includes instruction prefetch misses and instruction demand fetch misses.

•Pfetch - Misses Per Kinst

This is the number of instruction line prefetch requests (streaming and non-streaming) that miss the L2 instruction cache per 1000 retired instructions, including nops and predicated off instructions.

•Dfetch - Misses Per Kinst

This is the number of instruction demand requests that miss the L2 instruction cache per 1000 retired instructions, including nops and predicated off instructions.

l2icache Event Set 239