1.\" Copyright (c) 2007 Joseph Koshy. All rights reserved. 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 13.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 14.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 15.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 16.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 17.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 18.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 19.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 20.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 21.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 22.\" SUCH DAMAGE. 23.\" 24.Dd November 25, 2007 25.Dt PMC_READ 3 26.Os 27.Sh NAME 28.Nm pmc_read , 29.Nm pmc_rw , 30.Nm pmc_write 31.Nd read and write hardware performance counters 32.Sh LIBRARY 33.Lb libpmc 34.Sh SYNOPSIS 35.In pmc.h 36.Ft int 37.Fn pmc_read "pmc_id_t pmc" "pmc_value_t *value" 38.Ft int 39.Fn pmc_rw "pmc_id_t pmc" "pmc_value_t newvalue" "pmc_value_t *oldvaluep" 40.Ft int 41.Fn pmc_write "pmc_id_t pmc" "pmc_value_t value" 42.Sh DESCRIPTION 43These functions read and write the current value of a PMC. 44.Pp 45Function 46.Fn pmc_read 47will read the current value of the PMC specified by argument 48.Fa pmc 49and write it to the location specified by argument 50.Fa value . 51.Pp 52Function 53.Fn pmc_write 54will set the current value of the PMC specified by argument 55.Fa pmc 56to the value specified by argument 57.Fa value . 58.Pp 59Function 60.Fn pmc_rw 61combines a read and a write into a single atomic operation. 62.Pp 63For write operations the PMC should be a quiescent state. 64.Sh RETURN VALUES 65.Rv -std 66.Sh ERRORS 67A call to these functions may fail with the following errors: 68.Bl -tag -width Er 69.It Bq Er EBUSY 70A write operation specified a currently running PMC. 71.It Bq Er EINVAL 72Argument 73.Fa pmc 74specified a PMC not in a readable state. 75.It Bq Er EINVAL 76The PMC specified by argument 77.Fa pmc 78was not owned by the current process. 79.El 80.Sh SEE ALSO 81.Xr pmc 3 , 82.Xr hwpmc 4 83