*** UNIX MANUAL PAGE BROWSER ***

PMC_READ(3) FreeBSD 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) FreeBSD 14.1-RELEASE-p8 November 25, 2007 FreeBSD 14.1-RELEASE-p8