|
NAME | SYNOPSIS | DESCRIPTION | MODIFIERS | AUTHORS | COLOPHON |
LIBPFM(3) Linux Programmer's Manual LIBPFM(3)
libpfm_perf_event_raw - support for perf_events raw events syntax
#include <perfmon/pfmlib.h>
PMU name: perf_raw
PMU desc: Raw perf_events event syntax
The library supports a pseudo PMU model to allow raw encodings of PMU
events for the Linux perf_events kernel interface.
With this PMU, it is possible to provide the raw hexadecimal encoding
of any hardware event for any PMU models. The raw encoding is passed
as is to the kernel. All events are encoded as PERF_TYPE_RAW. As
such, perf_events generic events, such as cycles, instructions,
cannot be encoded by this PMU.
The syntax is very simple: rX. X is the hexadecimal 64-bit value for
the event. It may include event filters on some PMU models. The
hexadecimal number is passed without the 0x prefix, e.g., r01c4.
The library's standard perf_events attributes are supported by this
PMU model. They are separated with colons as is customary with the
library.
The following modifiers are supported by this PMU model:
u Measure at user level which includes privilege levels 1, 2, 3.
This corresponds to PFM_PLM3. This is a boolean modifier.
k Measure at kernel level which includes privilege level 0. This
corresponds to PFM_PLM0. This is a boolean modifier.
h Measure at the hypervisor level. This corresponds to PFM_PLMH.
This is a boolean modifier
mg Measure guest execution only. This is a boolean modifier
mh Measure host execution only. This is a boolean modifier
period Specify the the sampling period value. Value can be expressed
in decimal or hexadecimal. Value is 64-bit wide. This option
is mutually exclusive with freq. The period is expressed in
the unit of the event. There is no default value.
freq Specify the the sampling frequency value. Value can be
expressed in decimal or hexadecimal. Value is 64-bit wide.
This options is mutually exclusive with period. The value is
expressed in Hertz. For instance, freq=100, means that the
event should be sampled 100 times per second on average. There
is no default value.
excl The associated event is the only event measured on the PMU.
This applies only to hardware events. This attribute requires
admin privileges. Default is off.
precise
Enables precise sampling mode. This option is only valid when
sampling on events. The options takes an integer argument. It
can have the following values: 1=enable precise sampling,
2=enable precise sampling and eliminate skid, 3=enable precise
sampling, eliminate skid and bias. Not all events necessarily
support precise mode at all levels, this is dependent on the
underlying PMU. Eliminating skid is a best effort feature. It
may not work for all samples. This option is mutually
exclusive with hw_smpl. This options implies using the
hardware assist sampling mechanism.
hw_smpl
Enables hardware assist sampling. This is a boolean option. It
is false by default. On some processors, it is possible to
have the hardware record samples in a buffer and then notify
the kernel when it is full. Such feature may not be available
for all events. Using a hardware buffer does not necessarily
eliminate skid and bias, it usually lowers the overhead of
interrupt-based sampling by amortizing the interrupt over
multiple samples. This option is usually implicit with precise
sampling events.
cpu This integer option is used with system-wide events, i.e.,
events attached to a CPU instead of a thread. The value
designate the CPU to attach the event to. It is up to the
caller of the library to use the cpu field in the library
event encoding argument to create the event. No verification
on the validity of the CPU number is made by the library.
Default value is -1 for this field.
pinned This boolean option is used with system-wide events, i.e.,
events attached to a CPU instead of a thread. If set, then the
event is marked as pinned. That means it needs to remain on
the counters at all time, i.e., it cannot be multiplexed.
There can only be as many pinned events as there are counters,
yet the library does not check for that, the perf_event
subsystem does. The default value for this field is false,
i.e., the event is not pinned.
Stephane Eranian <eranian@gmail.com>
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 perfmon2-libpfm4⟩ on
2020-08-13. (At that time, the date of the most recent commit that
was found in the repository was 2020-08-12.) If you discover 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
February, 2014 LIBPFM(3)