diff -ur ctxbench-1.9.orig/ctxbench.c ctxbench-1.9/ctxbench.c
--- ctxbench-1.9.orig/ctxbench.c	2002-12-09 22:41:59.000000000 +0100
+++ ctxbench-1.9/ctxbench.c	2008-03-28 10:30:55.000000000 +0100
@@ -1,19 +1,28 @@
+#include <sched.h>
 #include <time.h>
 #include <errno.h>
 #include <stdio.h>
 #include <signal.h>
 #include <unistd.h>
-#include <sched.h>
 #include <sys/types.h>
 #include <sys/time.h>
 #include <sys/shm.h>
 #include <sys/sem.h>
 #include <sys/msg.h>
 #include <sys/stat.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 
 /* this should be in unistd.h!! */
 /* #include <getopt.h> */
 
+/**************** Prototypes */
+
+void shmchild(int shm, int semid);
+void shmparent(int shm, int semid, pid_t child);
+void do_cpubind(int cpu);
+
 /**************** General internal procs and flags here */
 /*		help/usage */
 static void usage(void);
@@ -25,7 +34,6 @@
 int Niter = 0;
 /*		Use signals rather than semiphores */
 static void sig_NOP();
-static void wait_sig();
 int OkayToRun = 0;
 int ParentPID, ChildPID;
 /*		pipe vectors for -p option */
@@ -79,19 +87,20 @@
 
 int msgqid;
 int do_yield = 0;
-
-main(int argc, char *argv[])
+
+int main(int argc, char *argv[])
 {
 	int shm;
 	struct shmid_ds buf;
 	int semid = -1;
-	int child, stat;
+	int cpubind = -1;
+	int child;
 	int RunTime = 10;
 	union semun pvt_semun;
 
 	pvt_semun.val = 0;
 
-	while ((shm = getopt(argc, argv, "sSLYmpn:t:")) != EOF) {
+	while ((shm = getopt(argc, argv, "sSLYmpn:t:c:")) != EOF) {
 		switch (shm) {
 		/* these are IPC types */
 		case 's':	/* use semiphore */
@@ -124,11 +133,14 @@
 		case 't':	/* give time to run */
 			RunTime = atoi(optarg);
 			break;
+		case 'c':	/* bind to a specific cpu */
+			cpubind = atoi(optarg);
+			break;
 		default:	/* typo */
 			usage();
 		}
 	}
-
+
 	signal(SIGALRM, timeout);
 	if (RunTime) alarm(RunTime);
 
@@ -164,7 +176,7 @@
 	}
 
 	/* identify version and method */
-	printf("\n\nContext switching benchmark v1.17\n");
+	printf("\n\nContext switching benchmark v1.17-cpubind\n");
 	printf("  Using %s for IPC control\n", IPCname[IPCtype]);
 
 	printf("   Max iterations: %8d (zero = no limit)\n", Iterations);
@@ -174,13 +186,14 @@
 
 	ParentPID = getpid();
 	if ((child = fork()) == 0) {
+		do_cpubind(cpubind);
 		ChildPID = getpid();
 		shmchild(shm, semid);
 	} else {
+		do_cpubind(cpubind);
 		ChildPID = child;
 		shmparent(shm, semid, child);
 	}
-
 	wait(NULL);
 	if (shmctl(shm, IPC_RMID, &buf) != 0) {
 		perror("Error removing shared memory");
@@ -215,14 +228,13 @@
 		break;
 	}
 
-	exit(0);
+	return 0;
 }
-
 
 /*******************************/
 /*  child using IPC method */
 
-int shmchild(int shm, int semid)
+void shmchild(int shm, int semid)
 {
 	volatile char *mem;
 	int num = 0;
@@ -313,7 +325,7 @@
 /********************************/
 /*  parent using shared memory  */
 
-int shmparent(int shm, int semid, pid_t child)
+void shmparent(int shm, int semid, pid_t child)
 {
 	volatile char *mem;
 	int num = 0;
@@ -328,7 +340,7 @@
 
 
 	if (!(mem = shmat(shm, 0, 0))) {
-		perror("shmchild: Error attaching shared memory");
+		perror("shmparent: Error attaching shared memory");
 		exit(2);
 	}
 
@@ -439,7 +451,7 @@
 		exit(3);
 	}
 }
-
+
 /*****************************************************************
  | usage - give the user a clue
  ****************************************************************/
@@ -458,6 +470,7 @@
 		" -p   use pipes for IPC\n"
 		" -L   spinLock in shared memory\n"
 		" -Y   spinlock with sched_yield (for UP)\n"
+		" -cN  bind to cpu N\n"
 		"\nRun limit options:\n"
 		" -nN  limit loops to N (default via timeout)\n"
 		" -tN  run for N sec, default 10\n\n"
@@ -490,3 +503,22 @@
 	signal(SIGUSR1, sig_NOP);
 	return;
 }
+
+/*****************************************************************
+ | cpu_bind - bind all tasks to a given cpu
+ ****************************************************************/
+
+void do_cpubind(int cpubind)
+{
+	if (cpubind >= 0) {
+		cpu_set_t d;
+		int ret;
+
+		CPU_ZERO(&d);
+		CPU_SET(cpubind, &d);
+		ret = sched_setaffinity(0, sizeof(d), &d);
+		printf("%d: sched_setaffinity %d: %lxh\n",getpid(), ret, *((int*)&d));
+		ret = sched_getaffinity(0, sizeof(d), &d);
+		printf("%d: sched_getaffinity %d: %lxh\n",getpid(), ret, *((int*)&d));
+	}
+}