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pmc_rw(3) [freebsd man page]

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

Check Out this Related Man Page

PMC_START(3)						   BSD Library Functions Manual 					      PMC_START(3)

NAME
pmc_start, pmc_stop -- start and stop a PMC LIBRARY
Performance Counters Library (libpmc, -lpmc) SYNOPSIS
#include <pmc.h> int pmc_start(pmc_id_t pmc); int pmc_stop(pmc_id_t pmc); DESCRIPTION
These functions are used to start and stop a PMC. Function pmc_start() starts the PMC specified by argument pmc. If the specified PMC has process scope and has not been attached to any tar- gets, it will be attached to the current process. Function pmc_stop() stops the PMC specified by argument pmc. 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: [EDOOFUS] Function pmc_start() specified a PMC that requires a log file and no log file was configured. [EINVAL] The specified PMC is in the process of being deleted. [EINVAL] Function pmc_stop() specified a PMC that was never started. [ENXIO] The specified PMC had system scope and its associated CPU was disabled or absent. SEE ALSO
pmc(3), hwpmc(4) BSD
September 22, 2008 BSD

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