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libpfm_core

NAME

libpfm_core - support for Intel Core processor family

SYNOPSIS

 #include <perfmon/pfmlib.h>
 #include <perfmon/pfmlib_core.h>
 
 

 

DESCRIPTION

The libpfm library provides full support for the Intel Core processor family, including the Core 2 Duo and Quad series. The interface is defined in pfmlib_core.h. It consists of a set of functions and structures which describe and allow access to the Intel Core processors specific PMU features.

When Intel Core processor specific features are needed to support a measurement, their descriptions must be passed as model-specific input arguments to the pfm_dispatch_events() function. The Intel Core processors specific input arguments are described in the pfmlib_core_input_param_t structure. No output parameters are currently defined. The input parameters are defined as follows:

 typedef struct {
         unsigned int    cnt_mask;
         unsigned int    flags;
 } pfmlib_core_counter_t;
 
 typedef struct {
         unsigned int pebs_used;
 } pfmlib_core_pebs_t;
 
 typedef struct {
         pfmlib_core_counter_t   pfp_core_counters[PMU_CORE_NUM_COUNTERS];
         pfmlib_core_pebs_t      pfp_core_pebs;
         uint64_t                reserved[4];
 } pfmlib_core_input_param_t;
 

The Intel Core processor provides a few additional per-event features for counters: thresholding, inversion, edge detection. They can be set using the pfp_core_counters data structure for each event. The flags field can be initialized with any combinations of the following values:

PFMLIB_CORE_SEL_INV

Inverse the results of the cnt_mask comparison when set

PFMLIB_CORE_SEL_EDGE

Enables edge detection of events.

The cnt_mask field is used to set the event threshold. The value of the counter is incremented each time the number of occurrences per cycle of the event is greater or equal to the value of the field. Thus the event is modified to actually measure the number of qualifying cycles. When zero all occurrences are counted (this is the default).

Support for Precise-Event Based Sampling (PEBS)

The library can be used to setup the PMC registers when using PEBS. In this case, the pfp_core_pebs structure must be used and the pebs_used field must be set to 1. When using PEBS, it is not possible to use more than one event.

Support for Intel Core 2 Duo and Quad processors

The Intel Core 2 Duo and Quad processors are based on the Intel Core micro-architecture. They implement the Intel architectural PMU and some extensions such as PEBS. They support all the architectural events and a lot more Core 2 specific events. The library auto-detects the processor and provides access to Core 2 events whenever possible.

ERRORS

Refer to the description of the pfm_dispatch_events() function for errors.

SEE ALSO

pfm_dispatch_events(3) and set of examples shipped with the library

AUTHOR

Stephane Eranian <eranian@hpl.hp.com>