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