1 /*- 2 * Copyright (c) 2014, Neville-Neil Consulting 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * Author: George V. Neville-Neil 27 * 28 */ 29 30 /* 31 * Calculate the time overhead of starting, stopping, and recording 32 * pmc counters. 33 * 34 * The only argument is a counter name, such as "instruction-retired" 35 * which is CPU dependent and can be found with pmmcontrol(8) using 36 * pmccontrol -L. 37 * 38 * The start, stop, read and write operations are timed using the 39 * rdtsc() macro which reads the Time Stamp Counter on the CPU. 40 */ 41 42 #include <stdio.h> 43 #include <err.h> 44 #include <sysexits.h> 45 #include <sys/types.h> 46 #include <machine/cpufunc.h> 47 #include <pmc.h> 48 49 int 50 main(int argc, char **argv) 51 { 52 pmc_id_t pmcid; 53 pmc_value_t read_value; 54 pmc_value_t read_clear_value; 55 uint64_t tsc1, write_cyc, start_cyc, read_cyc, stop_cyc; 56 char *counter_name; 57 58 if (argc != 2) 59 err(EX_USAGE, "counter-name required"); 60 61 counter_name = argv[1]; 62 63 if (pmc_init() != 0) 64 err(EX_OSERR, "hwpmc(4) not loaded, kldload or update your kernel"); 65 66 if (pmc_allocate(counter_name, PMC_MODE_SC, 0, 0, &pmcid, 64*1024) < 0) 67 err(EX_OSERR, "failed to allocate %s as a system counter in counting mode", 68 counter_name); 69 70 tsc1 = rdtsc(); 71 if (pmc_write(pmcid, 0) < 0) 72 err(EX_OSERR, "failed to zero counter %s", counter_name); 73 write_cyc = rdtsc() - tsc1; 74 75 tsc1 = rdtsc(); 76 if (pmc_start(pmcid) < 0) 77 err(EX_OSERR, "failed to start counter %s", counter_name); 78 start_cyc = rdtsc() - tsc1; 79 80 tsc1 = rdtsc(); 81 if (pmc_read(pmcid, &read_value) < 0) 82 err(EX_OSERR, "failed to read counter %s", counter_name); 83 read_cyc = rdtsc() - tsc1; 84 85 tsc1 = rdtsc(); 86 if (pmc_stop(pmcid) < 0) 87 err(EX_OSERR, "failed to stop counter %s", counter_name); 88 stop_cyc = rdtsc() - tsc1; 89 90 if (pmc_rw(pmcid, 0, &read_clear_value)) 91 err(EX_OSERR, "failed to read and zero %s", counter_name); 92 93 if (pmc_release(pmcid) < 0) 94 err(EX_OSERR, "failed to release %s as a system counter in counting mode", 95 counter_name); 96 97 printf("Counter %s, read value %ld, read/clear value %ld\n", 98 counter_name, read_value, read_clear_value); 99 printf("Cycles to start: %ld\tstop: %ld\tread: %ld\twrite: %ld\n", 100 start_cyc, stop_cyc, read_cyc, stop_cyc); 101 102 return(0); 103 } 104 105