-h counter_definition_1 ...[,counter_definition_n]

Collect hardware counter overflow profiling data. The number of counter definitions is processor-dependent. This option is now available on systems running the Linux operating system if you have installed the perfctr patch, which you can download from http://user.it.uu.se/~mikpe/linux/perfctr/2.6/perfctr-2.6.15.tar.gz .

A counter definition can take one of the following forms, depending on whether the processor supports attributes for hardware counters.

[+]counter_name[/ register_number][,interval ]

[+]counter_name[~ attribute_1=value_1]...[~attribute_n =value_n][/ register_number][,interval ]

The processor-specific counter_name can be one of the following:

• A well-known (aliased) counter name

• A raw (internal) name, as used by cputrack(1). If the counter can use either event register, the event register to be used can be specified by appending /0 or /1 to the internal name.

If you specify more than one counter, they must use different registers. If they do not use different registers, the collect command prints an error message and exits. Some counters can count on either register.

To obtain a list of available counters, type collect with no arguments in a terminal window. A description of the counter list is given in the section Hardware Counter Lists.

If the hardware counter counts events that relate to memory access, you can prefix the counter name with a + sign to turn on searching for the true program counter address (PC) of the instruction that caused the counter overflow. This backtracking works on SPARC processors, and only with counters of type load , store , or load-store. If the search is successful, the virtual PC, the physical PC, and the effective address that was referenced are stored in the event data packet.

On some processors, attribute options can be associated with a hardware counter. If a processor supports attribute options, then running the collect command with no arguments lists the counter definitions including the attribute names. You can specify attribute values in decimal or hexadecimal format.

The interval (overflow value) is the number of events counted at which the hardware counter overflows and the overflow event is recorded. The interval can be set to one of the following:

• on, or a null string– The default overflow value, which you can determine by typing collect with no arguments.

• hi[gh]– The high-resolution value for the chosen counter, which is approximately ten times shorter than the default overflow value. The abbreviation h is also supported for compatibility with previous software releases.

• lo[w]– The low-resolution value for the chosen counter, which is approximately ten times longer than the default overflow value.

• interval– A specific overflow value, which must be a positive integer and can be in decimal or hexadecimal format.

The default is the normal threshold, which is predefined for each counter and which appears in the counter list. See also Limitations on Hardware Counter Overflow Profiling.

If you use the -h option without explicitly specifying a-p option, clock-based profiling is turned off. To collect both hardware counter data and clock-based data, you must specify both a -h option and a -p option.