NAME¶

pfm_find_event, pfm_find_full_event, pfm_find_event_bycode, pfm_find_event_bycode_next, pfm_find_event_mask - search for events and unit masks

SYNOPSIS¶

#include <perfmon/pfmlib.h>

int pfm_find_event(const char *str, unsigned int *desc);
int pfm_find_full_event(const char *str, pfmlib_event_t *e);
int pfm_find_event_bycode(int code, unsigned int *desc);
int pfm_find_event_bycode_next(unsigned int desc1, int code, unsigned int *desc);
int pfm_find_event_mask(unsigned int idx, const char *str, unsigned int *mask_idx);

DESCRIPTION¶

The PMU counters can be programmed to count the number of occurrences of certain events. The number of events varies from one PMU model to the other. Each event has a name and a code which is used to program the actual PMU register. Some event may need to be further qualified with unit masks.

The library does not directly expose the event code, nor unit mask code, to user applications because it is not necessary. Instead applications use names to query the library for particular information about events. Given an event name, the library returns an opaque descriptor. Each descriptor is unique and has no relationship to the event code.

The set of functions described here can be used to get an event descriptor given either the name of the event or its code. Several events may share the same code. An event name is a string structured as: event_name[:unit_mask1[:unit_mask2]].

The pfm_find_event() function is a general purpose search routine. Given an event name in str, it returns the descriptor for the corresponding event. If unit masks are provided, they are not taken into account. This function is being deprecated in favor of the pfm_find_full_event() function.

The pfm_find_full_event() function is the general purpose search routine. Given an event name in str, it returns in ev, the full event descriptor that includes the event descriptor in ev->event and the unit mask descriptors in ev->unit_masks. The number of unit masks descriptors returned is indicated in ev->num_masks. Unit masks are specified as a colon separated list of unit mask names, exact values or value combinations. For instance, if event A supports unit masks M1 (0x1) and M2 (0x40), and both unit masks are to be measured, then the following values for str are valid: "A:M1:M2", "A:M1:0x40", "A:M2:0x1", "A:0x1:0x40", "A:0x41".

The pfm_find_event_bycode() function searches for an event given its code represented as an integer. It returns in desc, the event code. Unit masks are ignored.

Because there can be several events with the same code, the library provides the pfm_find_event_bycode_next() function to search for other events with the same code. Given an event desc1 and a code, this function will look for the next event with the same code. If such an event exists, its descriptor will be stored into desc. It is not necessary to have called the pfm_find_event_bycode() function prior to calling this function. This function is fully threadsafe as it does not maintain any state between calls.

The pfm_find_event_mask() function is used to find the unit mask descriptor based on its name or numerical value passed in str for the event specified in idx. The numeric value must be an exact match of an existing unit mask value, i.e., all bits must match. Some events do not have unit masks, in which case this function returns an error.

RETURN¶

All functions return whether or not the call was successful. A return value of PFMLIB_SUCCESS indicates success, otherwise the value is the error code.

ERRORS¶

PFMLIB_ERR_NOINIT the library has not been initialized properly.

PFMLIB_ERR_INVAL

the event descriptor is invalid, or the pointer argument is NULL.

PFMLIB_ERR_NOTFOUND

no matching event or unit mask was found.

AUTHOR¶

Stephane Eranian <eranian@hpl.hp.com>