runtime/nepomuk/services/strigi/priority.cpp

   1 /* This file is part of the KDE Project
   2    Copyright (c) 2008 Sebastian Trueg <trueg@kde.org>
   3
   4    Parts of this file are based on code from Strigi
   5    Copyright (C) 2006-2007 Jos van den Oever <jos@vandenoever.info>
   6
   7    This library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Library General Public
   9    License version 2 as published by the Free Software Foundation.
  10
  11    This library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public License
  17    along with this library; see the file COPYING.LIB.  If not, write to
  18    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19    Boston, MA 02110-1301, USA.
  20 */
  21
  22 #include "priority.h"
  23
  24 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE
  26 #endif
  27
  28 #include <QtCore/QDebug>
  29
  30 #include <sys/time.h>
  31 #include <sys/resource.h>
  32
  33 #include <unistd.h>
  34 #include <sys/syscall.h>
  35 #include <errno.h>
  36
  37 #include <sched.h>
  38
  39
  40 #ifdef SYS_ioprio_set
  41 namespace {
  42 #ifndef IOPRIO_CLASS_IDLE
  43     enum {
  44         IOPRIO_CLASS_NONE,
  45         IOPRIO_CLASS_RT,
  46         IOPRIO_CLASS_BE,
  47         IOPRIO_CLASS_IDLE
  48     };
  49 #endif
  50
  51 #ifndef IOPRIO_WHO_PROCESS
  52     enum {
  53         IOPRIO_WHO_PROCESS = 1,
  54         IOPRIO_WHO_PGRP,
  55         IOPRIO_WHO_USER
  56     };
  57 #endif
  58
  59 #ifndef IOPRIO_CLASS_SHIFT
  60     const int IOPRIO_CLASS_SHIFT = 13;
  61 #endif
  62 }
  63 #endif
  64
  65
  66 bool lowerIOPriority()
  67 {
  68 #ifdef SYS_ioprio_set
  69     if ( syscall( SYS_ioprio_set, IOPRIO_WHO_PROCESS, 0, IOPRIO_CLASS_IDLE<<IOPRIO_CLASS_SHIFT ) < 0 ) {
  70         qDebug( "cannot set io scheduling to idle (%s). Trying best effort.\n",  strerror( errno ));
  71         if ( syscall( SYS_ioprio_set, IOPRIO_WHO_PROCESS, 0, 7|IOPRIO_CLASS_BE<<IOPRIO_CLASS_SHIFT ) < 0 ) {
  72             qDebug( "cannot set io scheduling to best effort.\n");
  73             return false;
  74         }
  75     }
  76     return true;
  77 #else
  78     return false;
  79 #endif
  80 }
  81
  82
  83 bool lowerPriority()
  84 {
  85     return !setpriority( PRIO_PROCESS, 0, 19 );
  86 }
  87
  88
  89 // FIXME: is this really useful? Should we better use SCHED_IDLE?
  90 bool lowerSchedulingPriority()
  91 {
  92 #ifdef SCHED_BATCH
  93     struct sched_param param;
  94     memset( &param, 0, sizeof(param) );
  95     param.sched_priority = 0;
  96     return !sched_setscheduler( 0, SCHED_BATCH, &param );
  97 #else
  98     return false;
  99 #endif
 100 }