1                 : /*
       2                 :  * Copyright (c) 2011 The Native Client Authors. All rights reserved.
       3                 :  * Use of this source code is governed by a BSD-style license that can be
       4                 :  * found in the LICENSE file.
       5                 :  */
       6                 : 
       7                 : /*
       8                 :  * Linux thread priority support.
       9                 :  */
      10                 : #include <errno.h>
      11                 : #include <sched.h>
      12                 : #include <stdio.h>
      13                 : #include <string.h>
      14                 : #include <sys/resource.h>
      15                 : 
      16                 : #include "native_client/src/shared/platform/nacl_log.h"
      17                 : #include "native_client/src/trusted/service_runtime/include/sys/nacl_nice.h"
      18                 : 
      19             294 : void NaClThreadNiceInit(void) {
      20             294 : }
      21                 : 
      22                 : /* Linux version - threads are processes, so use setpriority in lieu
      23                 :  * of RLIMIT_RTPRIO.
      24                 :  * This appears to be lockup-free. To enable the privileged realtime
      25                 :  * threads, /etc/security/limits.conf typically needs to include a
      26                 :  * line like this:
      27                 :  *     @audio    -      nice      -10
      28                 :  * Ubuntu systems (and others?) automatically grant audio group permission
      29                 :  * to user who login on the console.
      30                 :  */
      31                 : /* Linux realtime scheduling is pretty broken at this time. See
      32                 :  * http://lwn.net/Articles/339316/ for a useful overview.
      33                 :  */
      34               0 : int nacl_thread_nice(int nacl_nice) {
      35               0 :   const int kRealTimePriority = -10;
      36               0 :   const int kBackgroundPriority = 10;
      37               0 :   const int kNormalPriority = 0;
      38                 : 
      39               0 :   switch (nacl_nice) {
      40                 :     case NICE_REALTIME:
      41               0 :       if (0 == setpriority(PRIO_PROCESS, 0, kRealTimePriority)) {
      42               0 :         return 0;  /* success */
      43                 :       }
      44                 :       /* Sorry; no RT priviledges. Fall through to NICE_NORMAL */
      45                 :     case NICE_NORMAL:
      46               0 :       if (0 == setpriority(PRIO_PROCESS, 0, kNormalPriority)) {
      47               0 :         return 0;  /* success */
      48                 :       }
      49               0 :       break;
      50                 :     case NICE_BACKGROUND:
      51               0 :       if (0 == setpriority(PRIO_PROCESS, 0, kBackgroundPriority)) {
      52               0 :         return 0;  /* success */
      53                 :       }
      54               0 :       break;
      55                 :     default:
      56               0 :       NaClLog(LOG_WARNING, "nacl_thread_nice failed (bad nice value)\n");
      57               0 :       return -1;
      58                 :       break;
      59                 :   }
      60               0 :   return -1;
      61                 : }