I386_PMC_INFO(2) BSD/i386 System Calls Manual I386_PMC_INFO(2)NAME
i386_pmc_info, i386_pmc_startstop, i386_pmc_read — interface to CPU per‐
formance counters
LIBRARY
i386 Architecture Library (libi386, -li386)
SYNOPSIS
#include <sys/types.h>
#include <machine/sysarch.h>
#include <machine/specialreg.h>
int
i386_pmc_info(struct i386_pmc_info_args *ia);
int
i386_pmc_startstop(struct i386_pmc_startstop_args *ssa);
int
i386_pmc_read(struct i386_pmc_read_args *ra);
DESCRIPTION
These functions provide an interface to the CPU performance counters on
the 586-class and 686-class processors.
i386_pmc_info() will return information about the available CPU counters.
The information is returned in ia having the following structure:
struct i386_pmc_info_args {
int type;
int flags;
};
The type member describes the class of performance counters available.
Valid values are:
PMC_TYPE_NONE No PMC support
PMC_TYPE_I586 586-class CPUs
PMC_TYPE_I686 686-class Intel CPUs
PMC_TYPE_K7 686-class AMD CPUs
The flags member describes additional capabilities of the processor.
Valid values are:
PMC_INFO_HASTSC CPU has time-stamp counter
i386_pmc_startstop() is used to start and stop the measurement of the CPU
performance counters. The argument ssa has the following structure:
struct i386_pmc_startstop_args {
int counter;
uint64_t val;
uint8_t event;
uint8_t unit;
uint8_t compare;
uint8_t flags;
};
The counter specified by the member counter is started if the member
flags has PMC_SETUP_KERNEL or PMC_SETUP_USER set, otherwise the counter
is stopped. The initial value of the counter is set to val. Additional
values for the flags member are PMC_SETUP_EDGE and PMC_SETUP_INV. The
event member specifies some event written to the control register. The
unit member specifies the measurement units. The compare member is a
mask for the counter.
i386_pmc_read() will return information about a specific CPU counter mea‐
sured during the last measurement period determined by the calling of
i386_pmc_startstop(). The information is returned in ra having the fol‐
lowing structure:
struct i386_pmc_read_args {
int counter;
uint64_t val;
uint64_t time;
};
The counter to read should be specified by the counter member. Counters
are numbered from 0 to PMC_NCOUNTERS. The value of the counter is
returned in the val member. The time since epoch, measured in CPU clock
cycles, is returned in the time member.
RETURN VALUES
Upon successful completion zero is returned, otherwise -1 is returned on
failure.
BSD November 10, 2001 BSD
