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PMC(3)		       FreeBSD Library Functions Manual			PMC(3)

NAME
     pmc -- library for	accessing hardware performance monitoring counters

LIBRARY
     Performance Monitoring Counters Interface Library (libpmc,	-lpmc)

SYNOPSIS
     #include <pmc.h>

DESCRIPTION
     Intel Pentium PMCs	are present in Intel Pentium and Pentium MMX proces-
     sors.  These PMCs are documented in the "Volume 3B: System	Programming
     Guide, Part 2", Intel 64 and IA-32	Intel(R) Architectures Software
     Developer's Manual, Order Number 253669-024US, Intel Corporation, August
     2007.

   PMC Features
     These CPUs	contain	two PMCs, each 40 bits wide.  These PMCs support the
     following capabilities:

     Capability		  Support
     PMC_CAP_CASCADE	  No
     PMC_CAP_EDGE	  No
     PMC_CAP_INTERRUPT	  No
     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

   Event Qualifiers
     Event specifiers for Intel	Pentium	PMCs can have the following common
     qualifiers:

     duration
	     Count duration (in	clocks)	of events.  The	default	is to count
	     events.

     os	     Measure events at privilege levels	0, 1 and 2.

     overflow
	     Assert the	external processor pin associated with a counter on
	     counter overflow.

     usr     Measure events at privilege level 3.

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

     Some events may only be used on specific counters and some	events are
     defined only on processors	supporting the MMX instruction set.  Note that
     these PMCs	do not have the	ability	to interrupt the CPU.

   Intel Pentium Event Specifiers
     The event specifiers supported by Intel Pentium PMCs are:

     p5-any-segment-register-loaded
	     (Event 0FH) The number of writes to any segment register, includ-
	     ing the LDTR, GDTR, TR and	IDTR.  Far control transfers and task
	     switches that involve privilege level changes will	count this
	     event twice.

     p5-bank-conflicts
	     (Event 0AH) The number of actual bank conflicts.

     p5-branches
	     (Event 12H) The number of taken and not taken branches including
	     branches, jumps, calls, software interrupts and interrupt
	     returns.

     p5-breakpoint-match-on-dr0-register
	     (Event 23H) The number of matches on the DR0 breakpoint register.

     p5-breakpoint-match-on-dr1-register
	     (Event 24H) The number of matches on the DR1 breakpoint register.

     p5-breakpoint-match-on-dr2-register
	     (Event 25H) The number of matches on the DR2 breakpoint register.

     p5-breakpoint-match-on-dr3-register
	     (Event 26H) The number of matches on the DR3 breakpoint register.

     p5-btb-false-entries
	     (Event 3AH, Pentium MMX) The number of false entries in the BTB.
	     This event	is only	allocated on counter 0.

     p5-btb-hits
	     (Event 13H) The number of branches	executed that hit in the
	     branch table buffer.

     p5-btb-miss-prediction-on-not-taken-branch
	     (Event 3AH, Pentium MMX) The number of times the BTB predicted a
	     not-taken branch as taken.	 This event is only allocated on
	     counter 1.

     p5-bus-cycle-duration
	     (Event 18H) The number of cycles while a bus cycle	was in
	     progress.

     p5-bus-ownership-latency
	     (Event 2AH, Pentium MMX) The time from bus	ownership being
	     requested to ownership being granted.  This event is only allo-
	     cated on counter 0.

     p5-bus-ownership-transfers
	     (Event 2AH, Pentium MMX) The number of bus	ownership transfers.
	     This event	is only	allocated on counter 1.

     p5-bus-utilization-due-to-processor-activity
	     (Event 2EH, Pentium MMX) The number of clocks the bus is busy due
	     to	the processor's	own activity.  This event is only allocated on
	     counter 0.

     p5-cache-line-sharing
	     (Event 2CH, Pentium MMX) The number of shared data	lines in L1
	     cache.  This event	is only	allocated on counter 1.

     p5-cache-m-state-line-sharing
	     (Event 2CH, Pentium MMX) The number of hits to an M- state	line
	     due to a memory access by another processor.  This	event is only
	     allocated on counter 0.

     p5-code-cache-miss
	     (Event 0EH) The number of instruction reads that miss the inter-
	     nal code cache.  Both cacheable and un-cacheable misses are
	     counted.

     p5-code-read
	     (Event 0CH) The number of instruction reads to both cacheable and
	     un-cacheable regions.

     p5-code-tlb-miss
	     (Event 0DH) The number of instruction reads that miss the
	     instruction TLB.  Both cacheable and un-cacheable unreads are
	     counted.

     p5-d1-starvation-and-fifo-is-empty
	     (Event 33H, Pentium MMX) The number of times the D1 stage cannot
	     issue any instructions because the	FIFO was empty.	 This event is
	     only allocated on counter 0.

     p5-d1-starvation-and-only-one-instruction-in-fifo
	     (Event 33H, Pentium MMX) The number of times the D1 stage could
	     issue only	one instruction	because	the FIFO had one instruction
	     ready.  This event	is only	allocated on counter 1.

     p5-data-cache-lines-written-back
	     (Event 06H) The number of data cache lines	that are written back,
	     including those caused by internal	and external snoops.

     p5-data-cache-tlb-miss-stall-duration
	     (Event 30H, Pentium MMX) The number of clocks the pipeline	is
	     stalled due to a data cache TLB miss.  This event is only allo-
	     cated on counter 1.

     p5-data-read
	     (Event 00H) The number of memory data reads, counting internal
	     data cache	hits and misses.  I/O and data memory accesses due to
	     TLB miss processing are not included.  Split cycle	reads are
	     counted individually.

     p5-data-read-miss
	     (Event 03H) The number of memory read accesses that miss the data
	     cache, counting both cacheable and	un-cacheable accesses.	Data
	     accesses that are part of TLB miss	processing are not included.
	     I/O accesses are not included.

     p5-data-read-miss-or-write-miss
	     (Event 29H) The number of data reads and writes that miss the
	     internal data cache, counting un-cacheable	accesses.  Data
	     accesses due to TLB miss processing are not counted.

     p5-data-read-or-write
	     (Event 28H) The number of data reads and writes including inter-
	     nal data cache hits and misses.  Data reads due to	TLB miss pro-
	     cessing are not counted.

     p5-data-tlb-miss
	     (Event 02H) The number of misses to the data cache	translation
	     look aside	buffer.

     p5-data-write
	     (Event 01H) The number of memory data writes, counting internal
	     data cache	hits and misses.  I/O is not included and split	cycle
	     writes are	counted	individually.

     p5-data-write-miss
	     (Event 04H) The number of memory write accesses that miss the
	     data cache, counting both cacheable and un-cacheable accesses.
	     I/O accesses are not counted.

     p5-emms-instructions-executed
	     (Event 2DH, Pentium MMX) The number of EMMS instructions exe-
	     cuted.  This event	is only	allocated on counter 0.

     p5-external-data-cache-snoop-hits
	     (Event 08H) The number of external	snoops to the data cache that
	     hit a valid line, or the data line	fill buffer, or	one of the
	     write back	buffers.

     p5-external-snoops
	     (Event 07H) The number of external	snoop requests accepted,
	     including snoops that hit in the code cache, the data cache and
	     that hit in neither.

     p5-floating-point-stalls-duration
	     (Event 32H, Pentium MMX) The number of cycles the pipeline	is
	     stalled due to a floating point freeze.  This event is only allo-
	     cated on counter 0.

     p5-flops
	     (Event 22H) The number of floating	point adds, subtracts, multi-
	     ples, divides and square roots.  Transcendental instructions
	     trigger this event	multiple times.	 Instructions generating
	     divide-by-zero, negative square root, special operand and stack
	     exceptions	are not	counted.  Integer multiply instructions	that
	     use the x87 FPU are counted.

     p5-full-write-buffer-stall-duration-while-executing-mmx-instructions
	     (Event 3BH, Pentium MMX) The number of clocks the pipeline	has
	     stalled due to full write buffers when executing MMX instruc-
	     tions.  This event	is only	allocated on counter 0.

     p5-hardware-interrupts
	     (Event 27H) The number of taken INTR and NMI interrupts.

     p5-instructions-executed
	     (Event 16H) The number of instructions executed.  Repeat prefixed
	     instructions are counted only once.  The HLT instruction is
	     counted only once,	irrespective of	the number of cycles spent in
	     the halted	state.	All hardware and software exceptions are
	     counted as	instructions, and fault	handler	invocations are	also
	     counted as	instructions.

     p5-instructions-executed-v-pipe
	     (Event 17H) The number of instructions that executed in the V
	     pipe.

     p5-io-read-or-write-cycle
	     (Event 1DH) The number of bus cycles directed to I/O space.

     p5-locked-bus-cycle
	     (Event 1CH) The number of locked bus cycles that occur on account
	     of	the lock prefixes, LOCK	instructions, page table updates and
	     descriptor	table updates.

     p5-memory-accesses-in-both-pipes
	     (Event 09H) The number of data memory reads or writes that	are
	     paired in both pipes.

     p5-misaligned-data-memory-or-io-references
	     (Event 0BH) The number of memory or I/O reads or writes that are
	     not aligned on natural boundaries.	 2- and	4-byte accesses	are
	     counted as	misaligned if they cross a 4 byte boundary.

     p5-misaligned-data-memory-reference-on-mmx-instructions
	     (Event 36H, Pentium MMX) The number of misaligned data memory
	     references	when executing MMX instructions.  This event is	only
	     allocated on counter 0.

     p5-mispredicted-or-unpredicted-returns
	     (Event 37H, Pentium MMX) The number of returns predicted incor-
	     rectly or not at all, only	counting RET instructions.  This event
	     is	only allocated on counter 0.

     p5-mmx-instruction-data-read-misses
	     (Event 31H, Pentium MMX) The number of MMX	instruction data read
	     misses.  This event is only allocated on counter 1.

     p5-mmx-instruction-data-reads
	     (Event 31H, Pentium MMX) The number of MMX	instruction data
	     reads.  This event	is only	allocated on counter 0.

     p5-mmx-instruction-data-write-misses
	     (Event 34H, Pentium MMX) The number of data write misses caused
	     by	MMX instructions.  This	event is only allocated	on counter 1.

     p5-mmx-instruction-data-writes
	     (Event 34H, Pentium MMX) The number of data writes	caused by MMX
	     instructions.  This event is only allocated on counter 0.

     p5-mmx-instructions-executed-u-pipe
	     (Event 2BH, Pentium MMX) The number of MMX	instructions executed
	     in	the U pipe.  This event	is only	allocated on counter 0.

     p5-mmx-instructions-executed-v-pipe
	     (Event 2BH, Pentium MMX) The number of MMX	instructions executed
	     in	the V pipe.  This event	is only	allocated on counter 1.

     p5-mmx-multiply-unit-interlock
	     (Event 38H, Pentium MMX) The number of clocks the pipeline	is
	     stalled because the destination of	a prior	MMX multiply is	not
	     ready.  This event	is only	allocated on counter 0.

     p5-movd-movq-store-stall-due-to-previous-mmx-operation
	     (Event 38H, Pentium MMX) The number of clocks a MOVD/MOVQ
	     instruction stalled in the	D2 stage of the	pipeline due to	a pre-
	     vious MMX instruction.  This event	is only	allocated on counter
	     1.

     p5-noncacheable-memory-reads
	     (Event 1EH) The number of bus cycles for non-cacheable instruc-
	     tion or data reads, including cycles caused by TLB	misses.

     p5-number-of-cycles-not-in-halt-state
	     (Event 30H, Pentium MMX) The number of cycles the processor is
	     not idle due to the HLT instruction.  This	event is only allo-
	     cated on counter 0.

     p5-pipeline-agi-stalls
	     (Event 1FH) The number of address generation interlock stalls.
	     An	AGI that occurs	in both	the U and V pipelines in the same
	     clock signals the event twice.

     p5-pipeline-flushes
	     (Event 15H) The number of pipeline	flushes	that occur.  Pipeline
	     flushes are caused	by branch mispredicts, exceptions, interrupts,
	     some segment register loads, and BTB misses.  Prefetch queue
	     flushes due to serializing	instructions are not counted.

     p5-pipeline-flushes-due-to-wrong-branch-predictions
	     (Event 35H, Pentium MMX) The number of pipeline flushes due to
	     wrong branch predictions resolved in either the E-	or WB- stage
	     of	the pipeline.  This event is only allocated on counter 0.

     p5-pipeline-flushes-due-to-wrong-branch-predictions-resolved-in-wb-stage
	     (Event 35H, Pentium MMX) The number of pipeline flushes due to
	     wrong branch predictions resolved in the stage of the pipeline.
	     This event	is only	allocated on counter 1.

     p5-pipeline-stall-for-mmx-instruction-data-memory-reads
	     (Event 36H, Pentium MMX) The number of clocks during pipeline
	     stalls caused by waiting MMX data memory reads.  This event is
	     only allocated on counter 1.

     p5-predicted-returns
	     (Event 37H, Pentium MMX) The number of predicted returns, whether
	     correct or	incorrect.  This counter only counts RET instructions.
	     This event	is only	allocated on counter 1.

     p5-returns
	     (Event 39H, Pentium MMX) The number of RET	instructions executed.
	     This event	is only	allocated on counter 0.

     p5-saturating-mmx-instructions-executed
	     (Event 2FH, Pentium MMX) The number of saturating MMX instruc-
	     tions executed.  This event is only allocated on counter 0.

     p5-saturations-performed
	     (Event 2FH, Pentium MMX) The number of saturating MMX instruc-
	     tions executed when at least one of its results were actually
	     saturated.	 This event is only allocated on counter 1.

     p5-stall-on-mmx-instruction-write-to-e-o-m-state-line
	     (Event 3BH, Pentium MMX) The number of clocks during stalls on
	     MMX instructions writing to E- or M- state	cache lines.  This
	     event is only allocated on	counter	1.

     p5-stall-on-write-to-an-e-or-m-state-line
	     (Event 1BH) The number of stalls on a write to an exclusive or
	     modified data cache line.

     p5-taken-branch-or-btb-hit
	     (Event 14H) The number of events that may cause a hit in the BTB,
	     namely either taken branches or BTB hits.

     p5-taken-branches
	     (Event 32H, Pentium MMX) The number of taken branches.  This
	     event is only allocated on	counter	1.

     p5-transitions-between-mmx-and-fp-instructions
	     (Event 2DH, Pentium MMX) The number of transitions	between	MMX
	     and floating-point	instructions and vice-versa.  This event is
	     only allocated on counter 1.

     p5-waiting-for-data-memory-read-stall-duration
	     (Event 1AH) The number of clocks the pipeline was stalled waiting
	     for data memory reads.  Data TLB misses processing	is included in
	     this count.

     p5-write-buffer-full-stall-duration
	     (Event 19H) The number of clocks while the	pipeline was stalled
	     due to write buffers being	full.

     p5-write-hit-to-m-or-e-state-lines
	     (Event 05H) The number of writes that hit exclusive or modified
	     lines in the data cache.

     p5-writes-to-noncacheable-memory
	     (Event 2EH, Pentium MMX) The number of writes to non-cacheable
	     memory, including write cycles caused by TLB misses and I/O
	     writes.  This event is only allocated on counter 1.

   Event Name Aliases
     The following table shows the mapping between the PMC-independent aliases
     supported by Performance Monitoring Counters Interface Library (libpmc,
     -lpmc) and	the underlying hardware	events used.

     Alias		   Event
     branches		   p5-taken-branches
     branch-mispredicts	   (unsupported)
     dc-misses		   p5-data-read-miss-or-write-miss
     ic-misses		   p5-code-cache-miss
     instructions	   p5-instructions-executed
     interrupts		   p5-hardware-interrupts
     unhalted-cycles	   p5-number-of-cycles-not-in-halt-state

SEE ALSO
     pmc(3), pmc.atom(3), pmc.core(3), pmc.core2(3), pmc.iaf(3), pmc.k7(3),
     pmc.k8(3),	pmc.p4(3), pmc.p6(3), pmc.soft(3), pmc.tsc(3), pmclog(3),
     hwpmc(4)

HISTORY
     The pmc library first appeared in FreeBSD 6.0.

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

FreeBSD	9.2			October	4, 2008			   FreeBSD 9.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | AUTHORS

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