diff -up irqbalance-0.55/irqbalance-0.55/irqbalance.c.orig irqbalance-0.55/irqbalance-0.55/irqbalance.c
--- irqbalance-0.55/irqbalance-0.55/irqbalance.c.orig	2006-11-23 14:53:22.000000000 -0500
+++ irqbalance-0.55/irqbalance-0.55/irqbalance.c	2008-03-18 06:33:03.000000000 -0400
@@ -22,7 +22,11 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <malloc.h>
+#include <fcntl.h>
+#include <string.h>
 #include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 #include "irqbalance.h"
 
@@ -52,6 +56,9 @@ void sleep_approx(int seconds)
 
 int main(int argc, char** argv)
 {
+	int pidf;
+	char buf[16];
+
 	if (argc>1 && strstr(argv[1],"debug"))
 		debug_mode=1;
 	if (argc>1 && strstr(argv[1],"oneshot"))
@@ -67,9 +74,9 @@ int main(int argc, char** argv)
 	if (getenv("IRQBALANCE_DEBUG")) 
 		debug_mode=1;
 
+	/* Initial parse to get correct core count */
 	parse_cpu_tree();
 
-
 	/* On single core UP systems irqbalance obviously has no work to do */
 	if (core_count<2) 
 		exit(EXIT_SUCCESS);
@@ -82,6 +89,19 @@ int main(int argc, char** argv)
 		if (daemon(0,0))
 			exit(EXIT_FAILURE);
 
+	pidf = open("/var/run/irqbalance.pid",O_RDWR|O_CREAT|O_EXCL,0666);
+	if (pidf < 0)
+		exit(EXIT_FAILURE);
+
+	snprintf(buf, 16, "%d", getpid());
+	if (write(pidf, buf, strlen(buf)) < strlen(buf)) {
+		close(pidf);
+		unlink("/var/run/irqbalance.pid");
+		exit(EXIT_FAILURE);
+	}
+
+	close(pidf);	
+
 	parse_proc_interrupts();
 	sleep(SLEEP_INTERVAL/4);
 	reset_counts();
@@ -134,5 +154,8 @@ int main(int argc, char** argv)
 			break;
 		counter++;
 	}
+
+	unlink("/var/run/irqbalance.pid");
+
 	return EXIT_SUCCESS;
 }