Intel CONTROLLERS 413808 - Manual (Page 734)

Intel ® 413808 and 413812—PMON Unit
Intel ® 413808 and 413812 I/O Controllers in TPER Mode
Developer’s Manual October 2007
734 Order Number: 317805-001US
16.4.2 Hardware Event Based Control
Hardware event based control allows a hardware event to control when another
command is executed. An example of this is controlling when a sample (snapshot) is
taken of the active counter(s). This is required to facilitate, among other things,
hardware data queue analysis . No command is executed until the command trigger
mux detects the event in the command trigger field of the command register. This
allows start, stop, sample, and other commands to be executed as a result of other
events happening.
Command Triggers refers to the ability of a command to be issued to the PMON unit,
and have it not be executed until the desired event, as programmed when the pending
command was issued, is detected.
The
PMON unit has no ability to queue commands so programming must be written so
as not to overwrite pending commands unless that is the desired effect.
For example, one could count how many memory reads happen before the first cache
hit occurs. This would be accomplished by programming the desired PMON counters to
start counting memory read events (Event A in Example 8 on page 735 ). Immediately
following that command the PMON controller is programmed to stop counting the
memory read events.