153 lines
4.5 KiB
C++
153 lines
4.5 KiB
C++
// ------------------------------------------------------------------------
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// kvu_rtcaps.h: Routines for utilizing POSIX RT extensions.
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// Copyright (C) 2001-2003,2009 Kai Vehmanen
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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// ------------------------------------------------------------------------
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <iostream>
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#include <unistd.h> /* getpid(), _POSIX_MEMLOCK */
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#ifdef HAVE_SCHED_H
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#include <sched.h>
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#endif
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#ifdef HAVE_SYS_MMAN_H
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#include <sys/mman.h> /* mlockall(), munlockall() */
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#endif
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#include <pthread.h>
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#include "kvu_rtcaps.h"
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static bool kvu_check_for_sched_sub(int policy);
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bool kvu_check_for_sched_sub(int policy)
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{
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bool result = false;
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#ifdef HAVE_SCHED_GETPARAM
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int curpid = getpid();
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/* store old scheduling params */
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struct sched_param prev_sparam;
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int ret = sched_getparam(curpid, &prev_sparam);
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if (ret == 0) {
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int prev_prio = prev_sparam.sched_priority;
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int prev_policy = sched_getscheduler(0);
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if (prev_policy >= 0) {
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/* get maximum priority for the tested policy */
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int min_prio = sched_get_priority_min(policy);
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if (min_prio >= 0) {
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struct sched_param sparam;
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sparam.sched_priority = min_prio;
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/* try to change scheduling according the new params */
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int ret = sched_setscheduler(curpid, policy, &sparam);
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if (ret == 0) {
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/* test succeeded, restore old settings */
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result = true;
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sparam.sched_priority = prev_prio;
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sched_setscheduler(curpid, prev_policy, &sparam);
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}
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}
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}
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}
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#else /* HAVE_SCHED_GETPARAM */
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std::cerr << "(libkvutils) kvu_rtcaps: warning! sched_getparam() not supported" << std::endl;
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#endif
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return(result);
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}
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/**
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* Checks whether current process has privileges
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* to set scheduler to SCHED_FIFO.
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*/
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bool kvu_check_for_sched_fifo(void)
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{
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#ifdef HAVE_SCHED_H
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return(kvu_check_for_sched_sub(SCHED_FIFO));
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#else
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std::cerr << "(libkvutils) kvu_rtcaps: warning! sched.h not available" << std::endl;
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#endif
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}
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/**
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* Checks whether current process has privileges
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* to set scheduler to SCHED_RR.
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*/
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bool kvu_check_for_sched_rr(void)
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{
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#ifdef HAVE_SCHED_H
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return(kvu_check_for_sched_sub(SCHED_RR));
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#else
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std::cerr << "(libkvutils) kvu_rtcaps: warning! sched.h not available" << std::endl;
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#endif
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}
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/**
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* Checks whether mlockall() call is available
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* and whether current process has privileges
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* to execute it.
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*
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* Note! Function issues an munlockall() call,
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* which will free all previously locked
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* memory areas for this process.
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*/
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bool kvu_check_for_mlockall(void)
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{
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bool result = false;
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#if defined(_POSIX_MEMLOCK) && defined(HAVE_MLOCKALL) && defined(HAVE_MUNLOCKALL) /* unistd.h */
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int ret = mlockall(MCL_CURRENT);
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if (ret == 0) {
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result = true;
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munlockall();
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}
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#else
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std::cerr << "(libkvutils) kvu_rtcaps: warning! POSIX_MEMLOCK not supported" << std::endl;
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#endif
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return(result);
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}
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/**
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* Sets the scheduler settings for calling thread.
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* If thread specific scheduler API (pthread_setscheduler, etc)
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* is not available, function will fall back to process level
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* functions (sched_setscheduler).
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*
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* @param policy SCHED_OTHER, SCHED_FIFO, SCHED_RR (see sched_setscheduler(2))
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* @param priority value between 0 and 99 (see sched_setscheduler(2))
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*
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* @return Zero on success, non-zero on error.
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*/
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int kvu_set_thread_scheduling(int policy, int priority)
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{
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int ret = 0;
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#if defined(HAVE_PTHREAD_SETSCHEDPARAM) && defined(HAVE_PTHREAD_SELF)
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struct sched_param sparam;
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sparam.sched_priority = priority;
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ret = pthread_setschedparam(pthread_self(), policy, &sparam);
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#elif defined(HAVE_SCHED_SETSCHEDULER)
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struct sched_param sparam;
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sparam.sched_priority = priority;
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ret = sched_setscheduler(0, policy, &sparam);
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#else
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std::cerr << "(libkvutils) kvu_rtcaps: warning! unable to set scheduler settings" << std::endl;
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#endif
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return ret;
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}
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