NAME | SYNOPSIS | DESCRIPTION | RETURN | ERRORS | AUTHOR | SEE ALSO | COLOPHON

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

NAME         top

       pfm_get_perf_event_encoding - encode event for perf_event API

SYNOPSIS         top

       #include <perfmon/pfmlib_perf_event.h>

       int pfm_get_perf_event_encoding(const char *str, int dfl_plm, struct perf_event_attr *attr, char **fstr, int *idx);

DESCRIPTION         top

       This function can be used in conjunction with the perf_events Linux
       kernel API which provides access to hardware performance counters,
       kernel software counters and tracepoints.  The function takes an
       event string in str and a default privilege level mask in dfl_plm and
       fills out the relevant parts of the perf_events specific data
       structure in attr.

       This function is deprecated. It is superseded by
       pfm_get_os_event_encoding() with the OS argument set to either
       PFM_OS_PERF_EVENT or PFM_OS_PERF_EVENT_EXT.  Using this function
       provides extended support for perf_events. Certain perf_event
       configuration option are only available through this new interface.

       The following examples illustrates the transition:

          struct perf_event_attr attr;
          int i, count = 0;
          uint64_t *codes;

          memset(&attr, 0, sizeof(attr));

          ret = pfm_get_perf_event_encoding("RETIRED_INSTRUCTIONS", PFM_PLM3, &attrs, NULL, NULL);
          if (ret != PFM_SUCCESS)
             err(1", cannot get encoding %s", pfm_strerror(ret));

       is equivalent to:

          #include <perfmon/pfmlib_perf_event.h>
          struct perf_event_attr attr;
          pfm_perf_encode_arg_t arg;

          memset(&arg, 0, sizeof(arg));
          arg.size = sizeof(arg);
          arg.attr = &attr;

          ret = pfm_get_os_event_encoding("RETIRED_INSTRUCTIONS", PFM_PLM3, PFM_OS_PERF, &arg);
          if (ret != PFM_SUCCESS)
             err(1", cannot get encoding %s", pfm_strerror(ret));

       The dfl_plm cannot be zero, though it may not necessarily be used by the event.
       Depending on the event, combination of the following privilege levels may be used:

       PFM_PLM3
              Measure at privilege level 3. This usually corresponds to user level. On X86, it corresponds
              to privilege levels 3, 2, 1. Check the PMU specific man page to verify if this level
              is supported by your PMU model.

       PFM_PLM2
              Measure at privilege level 2. Check the PMU specific man page to verify if this level
              is supported by your PMU model.

       PFM_PLM1
              Measure at privilege level 1. Check the PMU specific man page to verify if this level
              is supported by your PMU model.

       PFM_PLM0
              Measure at privilege level 0. This usually corresponds to kernel level. Check the PMU
              specific man page to verify if this level is supported by your PMU model.

       PFM_PLMH
              Measure at hypervisor privilege level. This is used in conjunction with hardware virtualization.
              Check the PMU specific man page to verify if this level is supported by your PMU model.

       If fstr is not NULL, the function will make it point to the fully qualified event string,
       i.e., a string with the event name, all unit masks set, and the value of all modifiers.
       The library will allocate memory to store the event string but it is the responsibility of the
       caller to eventually free that string using free().

       If idx is not NULL, it returns the corresponding unique event identifier.

       Only select fields are modified by the function, the others are untouched.
       The following fields in attr are modified:

       type   The type of the event

       config The encoding of the event

       exclude_user
              Whether or not user level execution should be excluded from monitoring. The definition
              of user is PMU model specific.

       exclude_kernel
              Whether or not kernel level execution should be excluded from monitoring. The definition
              of kernel is PMU model specific.

       exclude_hv
              Whether or not hypervisor level execution should be excluded from monitoring. The definition
              of hypervisor is PMU model specific.

       By default, if no privilege level modifier is specified in the event string, the library clears
       exclude_user, exclude_kernel and exclude_hv, resulting in the event being
       measured at all levels subject to hardware support.

       The function is able to work on only one event at a time. For convenience, it accepts
       event strings with commas. In that case, it will translate the first event up to the
       first comma. This is handy in case tools gets passed events as a comma-separated list.

RETURN         top

       The function returns in attr the perf_event encoding which
       corresponds to the event string. If idx is not NULL, then it will
       contain the unique event identifier upon successful return. The value
       PFM_SUCCESS is returned if successful, otherwise a negative error
       code is returned.

ERRORS         top

       PFM_ERR_TOOSMALL
              The code argument is too small for the encoding.

       PFM_ERR_INVAL
              The attr argument is NULL.

       PFM_ERR_NOMEM
              Not enough memory.

       PFM_ERR_NOTFOUND
              Event not found.

       PFM_ERR_ATTR
              Invalid event attribute (unit mask or modifier)

       PFM_ERR_ATTR_VAL
              Invalid modifier value.

       PFM_ERR_ATTR_SET
              attribute already set, cannot be changed.

       PFM_ERR_ATTR_UMASK
              Missing unit mask.

       PFM_ERR_ATTR_FEATCOMB
              Unit masks or features cannot be combined into a single event.

AUTHOR         top

       Stephane Eranian <eranian@gmail.com>

SEE ALSO         top

       pfm_get_os_event_encoding(3)

COLOPHON         top

       This page is part of the perfmon2 (a performance monitoring library)
       project.  Information about the project can be found at 
       ⟨http://perfmon2.sourceforge.net/⟩.  If you have a bug report for this
       manual page, send it to perfmon2-devel@lists.sourceforge.net.  This
       page was obtained from the project's upstream Git repository 
       ⟨git://git.code.sf.net/p/perfmon2/libpfm4⟩ on 2017-09-15.  If you dis‐
       cover any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
       you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

                               September, 2009                     LIBPFM(3)