pmc.tsc(3) [freebsd man page]

PMC.TSC(3)						   BSD Library Functions Manual 						PMC.TSC(3)

NAME

     pmc.tsc -- measurements using the i386 timestamp counter

LIBRARY

     Performance Counters Library (libpmc, -lpmc)

SYNOPSIS

     #include <pmc.h>

DESCRIPTION

     In the i386 architecture, the timestamp counter is a monotonically non-decreasing counter that counts processor cycles.

     This counter may be selected specifying an event specifier ``tsc'' to pmc_allocate(3).  The TSC is a read-only counter that may only be allo-
     cated in system-wide counting mode.  The ``tsc'' event does not support further event qualifiers.

     Multiple processes are allowed to allocate the TSC.  Once allocated, the TSC may be read using the pmc_read() function, or by using the RDTSC
     instruction.

   Event Name Aliases
     The alias ``cycles'' maps to the TSC.

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.p5(3), pmc.p6(3), pmc.soft(3), pmclog(3),
     hwpmc(4)

HISTORY

     The pmc library first appeared in FreeBSD 6.0.

AUTHORS

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

BSD
								  October 4, 2008							       BSD

PMC_READ(3)						   BSD Library Functions Manual 					       PMC_READ(3)

NAME

     pmc_read, pmc_rw, pmc_write, -- read and write hardware performance counters

LIBRARY

     Performance Counters Library (libpmc, -lpmc)

SYNOPSIS

     #include <pmc.h>

     int
     pmc_read(pmc_id_t pmc, pmc_value_t *value);

     int
     pmc_rw(pmc_id_t pmc, pmc_value_t newvalue, pmc_value_t *oldvaluep);

     int
     pmc_write(pmc_id_t pmc, pmc_value_t value);

DESCRIPTION

     These functions read and write the current value of a PMC.

     Function pmc_read() will read the current value of the PMC specified by argument pmc and write it to the location specified by argument
     value.

     Function pmc_write() will set the current value of the PMC specified by argument pmc to the value specified by argument value.

     Function pmc_rw() combines a read and a write into a single atomic operation.

     For write operations the PMC should be a quiescent state.

RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS

     A call to these functions may fail with the following errors:

     [EBUSY]		A write operation specified a currently running PMC.

     [EINVAL]		Argument pmc specified a PMC not in a readable state.

     [EINVAL]		The PMC specified by argument pmc was not owned by the current process.

SEE ALSO

     pmc(3), hwpmc(4)

BSD
								 November 25, 2007							       BSD