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int pfm_find_event(char *str, int *desc);
int pfm_find_event_byname(char *v, int *desc);
int pfm_find_event_bycode(int code, int *desc);
int pfm_find_event_bycode_next(int desc, int code, int *desc);
The PMU counters can be programmed to measure the number of occurrences
of certain events. The number of events varies from one implementation
to the other. Each event has a name and a code which is used to program
the actual PMU register. Not all event can necessarily be programmed on
any of the available counters due to hardware constraints.
The library does not directly expose the event code to user applica-
tions because it is not necessary. Instead applications used names to
query the library for particular information about events. Given a
name, the library returns an opaque descriptor to the applications.
Each descriptor is unique and has no relationship to the event code.
All functions requires the library to be properly initialized.
The set of functions described here allows to get an event descriptor
given either the name of the event or its code. Several events can
share the same code but have different names. In the current implemen-
tation of the PMU, an event code is composed of a base code (called
event select) and a umask. The combination of the two is guaranteed
unique. The umask is not an architected feature and as such is not part
of the generic interface of this library.
The pfm_find_event function is a general purpose search routine. Given
a string it returns the descriptor of the corresponding event. The
string can represent an event name or an event code in ASCII form.
Note that the code can be represented in decimal or hexadecimal.
In contrast pfm_find_event_byname searches for an event by interpreting
the name argument as the name event only.
Similarly, pfm_find_event_bycode searches for an event given its code
represented as an integer.
Because there can be several events with the same code, the library
provides the pfm_find_event_bycode_next to search for other events with
the same code. Given an event e and a code, this function will look for
the next event with the same code. It is not necessary to have called
pfm_find_event_bycode prior to calling this function. This function is
fully threadsafe as it does not maintain any state between calls.
All functions return whether or not the call was successful. A return
Stephane Eranian <email@example.com>
November, 2002 LIBPFM(3)