HP Caliper User's Guide

c2c Event Set
Available only on Itanium 2 and dual-core Itanium 2 systems.
The c2c (“cache-to-cache”) event set provides information relating to cache coherence
activity from the local processor perspective, the source of data for local data cache
misses, and rate at which the local processor satisfies the data cache miss of remote
processors.
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:
• Snoop Count
Counts snoops from the CPU or non-CPU (all snoops) for one sampling period.
• Hitm Count
Counts the number of bus snoop requests from remote processors that hit a
modified line in the local processor. Counts snoops from the CPU or non-CPU (all
snoops).
• Avg Snoop Stall Cycles
This is the average number of bus clocks that the Front Side Bus (FSB) is stalled
for a snoop.
• Avg Snoop Requests
This is the average number of live snoop responses that reside in the snoop request
queue per cycle.
• C2C/Snoop
This is the fraction of snoops that local processor detects that it has a modified
version of the data the a remote processor has requested as a result of a data cache
miss. It does not include implicit writebacks as a result of a modified hit on a line
that is being flushed in response to an fc instruction.
c2c Event Set 305