LIBPFM(3) Linux Programmer's Manual LIBPFM(3)NAME pfm_find_event - search for an event masks
SYNOPSIS
#include <perfmon/pfmlib.h>
int pfm_find_event(const char *str);
DESCRIPTION
This function is used to convert an event string passed in str into an
opaque event identifier, i.e., the return value.
Events are first manipulated a strings which contain the event name,
sub-event names and optional filters and modifiers. This function ana‐
lyzes the string and try to find the matching event.
The event string is a structured string and it is composed as follows:
[pmu_name::]event_name[:unit_mask][:modifer|:modifier=val]
The various components are separated by : or ::, they are defined as
follows:
pmu_name
This is an optional prefix to designte a specific PMU model.
With the prefix the event which matches the event_name is used.
In case multiple PMU models are activated, there may be conflict
with identical event names to mean the same or different things.
In that case, it is necessary to fully specify the event with a
pmu_name. That string corresponds to what is returned by
pfm_get_pmu_name().
event_name
This is the event name and is required. The library is not case
sensitive on event string. The event name must match completely
the actual event name; it cannot be a substring.
unit_mask
The optional unit mask which can be considered like a sub-event
of the major event. If a event has unit masks, and there is no
default, then at least one unit mask must be passed in the
string. Multiple unit masks may be specified for a single event.
modifier
A modifier is an optional filter which is provided by the hard‐
ware register hosting the event or by the underlying kernel in‐
frastructure. Typical modifiers include privilege level fil‐
ters. Some modifiers are simple boolean, in which case just
passing their names is equivalent to setting their value to
true. Other modifiers need a specific value, in which case it is
provided after the equal sign. No space is tolerate around the
equal sign. The list of modifiers depends on the host PMU and
underlying kernel API. They are documented in PMU-specific docu‐
mentation. Multiple modifiers may be passed. There is not order
between unit masks and modifiers.
The library uses the generic term attribute to designate both unit
masks and modifiers.
Here are a few examples of event strings:
amd64::RETIRED_INSTRUCTIONS:u
Event RETIRED_INSTRUCTION on AMD64 processor, measure at user
privilege level only
RS_UOPS_DISPATCHED:c=1:i:u
Event RS_UOPS_DISPATCHED measured at user privilege level only,
and with counter-mask set to 1
For the purpose of this function, only the pmu_name and event_name are
considered, everything else is parsed, thus must be valid, but is
ignored.
The function searches only for one event per call. As a convenience,
the function will identify the event up to the first comma. In other
words, if str is equal to "EVENTA,EVENTB", then the function will only
look at EVENTA and will not return an error because of invalid event
string. This is handy when parsing constant event strings containing
multiple, comma-separated, events.
RETURN
The function returns the opaque event identifier that corresponds that
the event string. In case of error, a negative error code is returned
instead.
ERRORS
PFMLIB_ERR_NOINIT
The library has not been initialized properly.
PFMLIB_ERR_INVAL
The event string is NULL.
PFMLIB_ERR_NOMEM
The library ran out of memory.
PFMLIB_ERR_NOTFOUND
The event was not found
PFMLIB_ERR_ATTR
Invalid event attribute
PFMLIB_ERR_ATTR_VAL
Invalid event attribute value
PFMLIB_ERR_TOOMANY
Too many event attributes passed
AUTHOR
Stephane Eranian <eranian@gmail.com>
September, 2009 LIBPFM(3)
