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/*
* Copyright 2017 International Business Machines
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <time.h>
#include <signal.h>
#include <sys/time.h>
#include <sched.h>
#include <utmpx.h>
#include "force_cpu.h"
/* FIXME Fake this for old RHEL versions e.g. RHEL5.6 */
#ifndef CPU_ALLOC
#define CPU_ALLOC(cpus) ({ void *ptr = NULL; ptr; })
#define CPU_ALLOC_SIZE(cpus) ({ int val = 0; val; })
#define CPU_ISSET_S(cpu, size, cpusetp) ({ int val = 0; val; })
#define CPU_FREE(cpusetp)
#define CPU_ZERO_S(size, cpusetp)
#define CPU_SET_S(run_cpu, size, cpusetp)
#define sched_getcpu() ({ int val = 0; val; })
#define sched_setaffinity(x, size, cpusetp) ({ int val = 0; val; })
#endif
void print_cpu_mask(void)
{
cpu_set_t *cpusetp;
size_t size;
int num_cpus, cpu;
num_cpus = CPU_SETSIZE; /* take default, currently 1024 */
cpusetp = CPU_ALLOC(num_cpus);
if (cpusetp == NULL)
return;
size = CPU_ALLOC_SIZE(num_cpus);
/* figure out on which cpus we might run now after change */
CPU_ZERO_S(size, cpusetp);
if (sched_getaffinity(0, size, cpusetp) < 0) {
CPU_FREE(cpusetp);
return;
}
for (cpu = 0; cpu < num_cpus; cpu += 1) {
if (!CPU_ISSET_S(cpu, size, cpusetp)) {
printf("\n");
break;
}
printf(" CPU: %4d = %s", cpu,
CPU_ISSET_S(cpu, size, cpusetp)?"yes":"no ");
if ((cpu & 0x3) == 0x3)
printf("\n");
}
CPU_FREE(cpusetp);
}
/**
* Try to ping process to a specific CPU. Returns the CPU we are
* currently running on.
*/
int pin_to_cpu(int run_cpu)
{
cpu_set_t *cpusetp;
size_t size;
int num_cpus;
num_cpus = CPU_SETSIZE; /* take default, currently 1024 */
cpusetp = CPU_ALLOC(num_cpus);
if (cpusetp == NULL) {
return sched_getcpu();
}
size = CPU_ALLOC_SIZE(num_cpus);
CPU_ZERO_S(size, cpusetp);
CPU_SET_S(run_cpu, size, cpusetp);
if (sched_setaffinity(0, size, cpusetp) < 0) {
CPU_FREE(cpusetp);
return sched_getcpu();
}
/* figure out on which cpus we actually run */
CPU_FREE(cpusetp);
return run_cpu;
}
int switch_cpu(int cpu, int verbose)
{
int new_cpu;
/* pin to specific CPU to get more precise performance measurements */
if (cpu < 0)
return 0;
if (verbose) {
printf("Default possible CPUs:\n");
print_cpu_mask();
printf("Running on CPU %d, want to run on CPU %d...\n",
sched_getcpu(), cpu);
}
new_cpu = pin_to_cpu(cpu);
if (new_cpu != cpu) {
fprintf(stderr, "err: desired CPU %d does not match current "
"CPU %d\n", cpu, new_cpu);
return -1;
}
if (verbose) {
printf("New possible CPUs:\n");
print_cpu_mask();
printf("Running on CPU %d\n", new_cpu);
}
return 0;
}
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