1LIBPFM(3)                  Linux Programmer's Manual                 LIBPFM(3)
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NAME

6       libpfm_core - support for Intel Atom processor family
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SYNOPSIS

9       #include <perfmon/pfmlib.h>
10       #include <perfmon/pfmlib_intel_atom.h>
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DESCRIPTION

14       The  libpfm library provides full support for the Intel Atom processor.
15       This processor implements Intel architectural perfmon v3  with  Precise
16       Event-Based Sampling (PEBS) support. It also implements all architected
17       events to which it adds lots of Atom specific events.
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19       The libpfm interface is defined in pfmlib_intel_atom.h. It consists  of
20       a  set  of  functions and structures which describe and allow access to
21       the Intel Atom processor specific PMU features.
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23       When Intel Atom processor specific features are  needed  to  support  a
24       measurement,  their descriptions must be passed as model-specific input
25       arguments to the pfm_dispatch_events() function. The Intel Atom proces‐
26       sors   specific   input   arguments   are   described   in   the   pfm‐
27       lib_intel_atom_input_param_t structure.  No output parameters are  cur‐
28       rently defined. The input parameters are defined as follows:
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30       typedef struct {
31            unsigned int   cnt_mask;
32            unsigned int   flags;
33       } pfmlib_intel_atom_counter_t;
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35       typedef struct {
36         pfmlib_intel_atom_counter_t pfp_intel_atom_counters[PMU_INTEL_ATOM_NUM_COUNTERS];
37         unsigned int                pfp_intel_atom_pebs_used;
38         uint64_t                    reserved[4];
39       } pfmlib_core_input_param_t;
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42       The Intel Atom processor provides several additional per-event features
43       for counters: thresholding, inversion, edge detection, monitoring  both
44       threads.  They can be set using the pfp_intel_atom_counters data struc‐
45       ture for each event.  The flags field can be initialized with any  com‐
46       binations of the following values:
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48       PFMLIB_INTEL_ATOM_SEL_INV
49              Inverse the results of the cnt_mask comparison when set
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51       PFMLIB_INTEL_ATOM_SEL_EDGE
52              Enable edge detection of events.
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54       PFMLIB_INTEL_ATOM_SEL_ANYTHR
55              Enable measuring the event in any of the two threads. By default
56              only the current thread is measured.
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58       The cnt_mask field is used to set the event threshold.   The  value  of
59       the  counter  is  incremented  each  time the number of occurrences per
60       cycle of the event is greater or equal to the value of the field.  Thus
61       the  event  is  modified  to  actually measure the number of qualifying
62       cycles.  When zero all occurrences are counted (this is the default).
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Support for Precise-Event Based Sampling (PEBS)

66       The library can be used to setup the PMC registers when using PEBS.  In
67       this  case,  the  pfp_intel_atom_pebs_used field must be set to 1. When
68       using PEBS, it is not possible to use more than one event.
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ERRORS

71       Refer to the description  of  the  pfm_dispatch_events()  function  for
72       errors.
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SEE ALSO

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

78       Stephane Eranian <eranian@gmail.com>
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80                                November, 2006                       LIBPFM(3)