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SubjectRE: sched_setaffinity not working with kernel 2.6.32.15
Date

Here's the correct testcase






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#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif

#include <stdio.h>
//#include <sched.h>
//#include <hwloc.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/syscall.h>

#define NR_CPUS 8
#define NR_THREADS 5
#define USE_THREADAFFINITY 1

pid_t tid[NR_THREADS];

pthread_barrier_t init_start, barrier2;

void print_affinity(pthread_t pid, int threadno) {
int i;
cpu_set_t set;
CPU_ZERO(&set);

sched_getaffinity( pid, sizeof(set), &set);

for( i = 0; i < NR_CPUS; i++) {
if (CPU_ISSET(i, &set))
printf("Cpu #%d is in %d thread's affinity\n", i, threadno);
}
}
void set_schedaffinity(pthread_t pid, int cpu) {
cpu_set_t set;
CPU_ZERO(&set);
CPU_SET(cpu, &set);

sched_setaffinity(pid, sizeof(set), &set);
}
void set_threadaffinity(pthread_t pid, int cpu) {
cpu_set_t set;
CPU_ZERO(&set);
CPU_SET(cpu, &set);

pthread_setaffinity_np(pid, sizeof(set), &set);
}
void * threadCode(void * threadNo) {
long int thread = (long int) threadNo;
if (!USE_THREADAFFINITY) {
//Set current thread id
tid[thread] = (pid_t) syscall (SYS_gettid);
//Wait for all the threads to set their thread id
pthread_barrier_wait(&init_start);
}
//Wait for main to set the affinity
pthread_barrier_wait(&barrier2);
//sleep(1);
//Print affinity
print_affinity(0,thread);
//Do something so that we can see cpu being used
while (1);
pthread_exit(0);
}


int main(int argc , char *argv[]) {
long int i;
pthread_t pid[NR_THREADS];
// Initialize barriers
if(pthread_barrier_init(&init_start, NULL, NR_THREADS+1)) {
printf("Could not create a barrier\n");
exit(1);
}
if(pthread_barrier_init(&barrier2, NULL, NR_THREADS+1)) {
printf("Could not create a barrier\n");
exit(1);
}
//Create threads
for (i = 0; i < NR_THREADS; i++)
pthread_create(&pid[i], NULL, threadCode, (void *) i);
//Wait for threads to set their thread id
if (!USE_THREADAFFINITY)
pthread_barrier_wait(&init_start);
//Set affinity
for (i = 0; i < NR_THREADS; i++) {
if (USE_THREADAFFINITY)
set_threadaffinity(pid[i],0);
else
set_schedaffinity(tid[i],0);
}
//Tell the threads to continue after setting affinity
pthread_barrier_wait(&barrier2);
getchar();
return 0;
}
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