view src/os/unix/ngx_setaffinity.c @ 5970:74edc0ccf27a

Core: fixed a race resulting in extra sem_post()'s. The mtx->wait counter was not decremented if we were able to obtain the lock right after incrementing it. This resulted in unneeded sem_post() calls, eventually leading to EOVERFLOW errors being logged, "sem_post() failed while wake shmtx (75: Value too large for defined data type)". To close the race, mtx->wait is now decremented if we obtain the lock right after incrementing it in ngx_shmtx_lock(). The result can become -1 if a concurrent ngx_shmtx_unlock() decrements mtx->wait before the added code does. However, that only leads to one extra iteration in the next call of ngx_shmtx_lock().
author Roman Arutyunyan <arut@nginx.com>
date Wed, 04 Feb 2015 16:22:43 +0300
parents f31162fefe01
children 7296b38f6416
line wrap: on
line source


/*
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


#if (NGX_HAVE_CPUSET_SETAFFINITY)

#include <sys/cpuset.h>

void
ngx_setaffinity(uint64_t cpu_affinity, ngx_log_t *log)
{
    cpuset_t    mask;
    ngx_uint_t  i;

    ngx_log_error(NGX_LOG_NOTICE, log, 0,
                  "cpuset_setaffinity(0x%08Xl)", cpu_affinity);

    CPU_ZERO(&mask);
    i = 0;
    do {
        if (cpu_affinity & 1) {
            CPU_SET(i, &mask);
        }
        i++;
        cpu_affinity >>= 1;
    } while (cpu_affinity);

    if (cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,
                           sizeof(cpuset_t), &mask) == -1)
    {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
                      "cpuset_setaffinity() failed");
    }
}

#elif (NGX_HAVE_SCHED_SETAFFINITY)

void
ngx_setaffinity(uint64_t cpu_affinity, ngx_log_t *log)
{
    cpu_set_t   mask;
    ngx_uint_t  i;

    ngx_log_error(NGX_LOG_NOTICE, log, 0,
                  "sched_setaffinity(0x%08Xl)", cpu_affinity);

    CPU_ZERO(&mask);
    i = 0;
    do {
        if (cpu_affinity & 1) {
            CPU_SET(i, &mask);
        }
        i++;
        cpu_affinity >>= 1;
    } while (cpu_affinity);

    if (sched_setaffinity(0, sizeof(cpu_set_t), &mask) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
                      "sched_setaffinity() failed");
    }
}

#endif