/*-
* Copyright (c) 2014, Neville-Neil Consulting
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* Author: George V. Neville-Neil
*
*/
/*
* Calculate the time overhead of starting, stopping, and recording
* pmc counters.
*
* The only argument is a counter name, such as "instruction-retired"
* which is CPU dependent and can be found with pmmcontrol(8) using
* pmccontrol -L.
*
* The start, stop, read and write operations are timed using the
* rdtsc() macro which reads the Time Stamp Counter on the CPU.
*/
#include <stdio.h>
#include <err.h>
#include <sysexits.h>
#include <sys/types.h>
#include <machine/cpufunc.h>
#include <pmc.h>
int
main(int argc, char **argv)
{
pmc_id_t pmcid;
pmc_value_t read_value;
pmc_value_t read_clear_value;
uint64_t tsc1, write_cyc, start_cyc, read_cyc, stop_cyc;
char *counter_name;
if (argc != 2)
err(EX_USAGE, "counter-name required");
counter_name = argv[1];
if (pmc_init() != 0)
err(EX_OSERR, "hwpmc(4) not loaded, kldload or update your kernel");
if (pmc_allocate(counter_name, PMC_MODE_SC, 0, 0, &pmcid, 64*1024) < 0)
err(EX_OSERR, "failed to allocate %s as a system counter in counting mode",
counter_name);
tsc1 = rdtsc();
if (pmc_write(pmcid, 0) < 0)
err(EX_OSERR, "failed to zero counter %s", counter_name);
write_cyc = rdtsc() - tsc1;
tsc1 = rdtsc();
if (pmc_start(pmcid) < 0)
err(EX_OSERR, "failed to start counter %s", counter_name);
start_cyc = rdtsc() - tsc1;
tsc1 = rdtsc();
if (pmc_read(pmcid, &read_value) < 0)
err(EX_OSERR, "failed to read counter %s", counter_name);
read_cyc = rdtsc() - tsc1;
tsc1 = rdtsc();
if (pmc_stop(pmcid) < 0)
err(EX_OSERR, "failed to stop counter %s", counter_name);
stop_cyc = rdtsc() - tsc1;
if (pmc_rw(pmcid, 0, &read_clear_value))
err(EX_OSERR, "failed to read and zero %s", counter_name);
if (pmc_release(pmcid) < 0)
err(EX_OSERR, "failed to release %s as a system counter in counting mode",
counter_name);
printf("Counter %s, read value %ld, read/clear value %ld\n",
counter_name, read_value, read_clear_value);
printf("Cycles to start: %ld\tstop: %ld\tread: %ld\twrite: %ld\n",
start_cyc, stop_cyc, read_cyc, stop_cyc);
return(0);
}
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