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PMC.IAF(3) MidnightBSD Library Functions Manual PMC.IAF(3)

pmc.iaf — measurement events for Intel fixed function performance counters.

Performance Counters Library (libpmc, -lpmc)

#include <pmc.h>

Intel fixed-function PMCs are present in CPUs that conform to version 2 or later of the Intel Performance Measurement Architecture. Each fixed-function PMC measures a specific hardware event. The number of fixed-function PMCs implemented in a CPU can vary. The number of fixed-function PMCs present can be determined at runtime by using function pmc_cpuinfo(3).

Intel fixed-function PMCs are documented in Volume 3: System Programming Guide, IA-32 Intel(R) Architecture Software Developer's Manual, Order Number 253669-027US, Intel Corporation, July 2008.

Fixed-function PMCs support the following capabilities:

PMC_CAP_CASCADE No
PMC_CAP_EDGE No
PMC_CAP_INTERRUPT Yes
PMC_CAP_INVERT No
PMC_CAP_READ Yes
PMC_CAP_PRECISE No
PMC_CAP_SYSTEM Yes
PMC_CAP_TAGGING No
PMC_CAP_THRESHOLD No
PMC_CAP_USER Yes
PMC_CAP_WRITE Yes

These PMCs are named using a class name prefix of “iaf-”.

These PMCs support the following modifiers:

Configure the PMC to count events occurring at ring level 0.
Configure the PMC to count events occurring at ring levels 1, 2 or 3.
(Atom CPUs) Configure the PMC to count events on all logical processors sharing a processor core. The default is to count events on the current logical processor.

If neither of the “os” or “usr” qualifiers are specified, the default is to enable both.

The fixed function PMCs are selectable using the following event names:

(Fixed Function Counter 0) The number of instructions retired.
(Fixed Function Counter 1) The number of core cycles for which the core is not halted.
(Fixed Function Counter 2) The number of reference cycles for which the core is not halted.

To measure the number of core cycles for which the core was not halted use the event specifier "iaf-cpu-clk-unhalted.core".

To measure the number of user instructions retired use the event specifier "iaf-instr-retired.any,usr".

To measure the number of user instructions retired on all logical processors in an Atom CPU, use the event specifier "iaf-instr-retired.any,usr,anythread".

pmc(3), pmc.atom(3), pmc.core(3), pmc.core2(3), pmc.k7(3), pmc.k8(3), pmc.p4(3), pmc.p5(3), pmc.p6(3), pmc.soft(3), pmc.tsc(3), pmc_cpuinfo(3), pmclog(3), hwpmc(4)

The pmc library first appeared in FreeBSD 6.0.

The Performance Counters Library (libpmc, -lpmc) library was written by Joseph Koshy <jkoshy@FreeBSD.org>.

November 14, 2008 midnightbsd-3.1