Re: sched_setscheduler() and usage issues ....please help

[Steven Rostedt <rostedt@goodmis.org>]

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On Tue, 2005-03-29 at 08:58 +0530, Arun Srinivas wrote:
> I am trying to set the SCHED_FIFO  policy for my process.I am using 
> sched_setscheduler() function to do this.

Attached is a little program that I use to set the priority of tasks.

-- Steve

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/* Copyright (C) 2004 Kihon Technologies Inc.

   This utilities is free software, you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   These utilities are distributed in the hope that they will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */
/*
 * Author: Steven Rostedt
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <strutils.h>
#include <errno.h>

void usage (char **argv)
{
	char *arg = argv[0];
	char *p = arg + strlen(arg);
	while (p >= arg && *p != '/') p--;
	p++;
	fprintf(stderr,"usage: %s pid policy priority\n"
			"\n\twhere policy is SCHED_RR, SCHED_FIFO or SCHED_OTHER\n"
			"\n", p);
	exit(-1);
}

int main (int argc, char **argv)
{
	pid_t pid;
	int policy;
	struct sched_param p;
	char *strpolicy;
	
	if (argc != 4)
		usage(argv);

	strpolicy = argv[2];
	pid = atoi(argv[1]);
	p.sched_priority = atoi(argv[3]);

	if (strcmp(strpolicy,"SCHED_RR")==0) {
		policy = SCHED_RR;
	} else if (strcmp(strpolicy,"SCHED_FIFO") == 0) {
		policy = SCHED_FIFO;
	} else if (strcmp(strpolicy,"SCHED_OTHER") == 0) {
		policy = SCHED_OTHER;
	} else {
		fprintf(stderr,"\nunknown policy %s",strpolicy);
		usage(argv);
	}

	if (sched_setscheduler(pid,policy,&p)) {
		perror("sched_setscheduler");
		exit(errno);
	}
	exit(0);
}