---
 include/linux/logdev_marker.h  |    2 +
 kernel/logdev/logdev_tracers.c |   76 +++++++++++++++++++++++++++++++++++++++++
 kernel/sched.c                 |    3 +
 3 files changed, 81 insertions(+)

Index: linux-2.6.21.5-rt20/include/linux/logdev_marker.h
===================================================================
--- linux-2.6.21.5-rt20.orig/include/linux/logdev_marker.h	2007-07-11 14:28:53.000000000 +0200
+++ linux-2.6.21.5-rt20/include/linux/logdev_marker.h	2007-07-11 14:28:56.000000000 +0200
@@ -53,6 +53,8 @@
 #ifdef CONFIG_LOGDEV_TRACING
 
 /* Place tracing prototypes here */
+void LDCALLER(context_switch) (struct task_struct *prev,
+			       struct task_struct *next);
 
 
 #endif /* CONFIG_LOGDEV_TRACING */
Index: linux-2.6.21.5-rt20/kernel/logdev/logdev_tracers.c
===================================================================
--- linux-2.6.21.5-rt20.orig/kernel/logdev/logdev_tracers.c	2007-07-11 14:28:53.000000000 +0200
+++ linux-2.6.21.5-rt20/kernel/logdev/logdev_tracers.c	2007-07-11 14:28:56.000000000 +0200
@@ -37,6 +37,28 @@ struct logdev_mark_hdr {
 
 /* ---------------- start here for user custom headers -------------------- */
 /* Add Tracing IDs and structures here */
+#define LOGMARK_EXAMPLE_ID 0xffff
+#define LOGMARK_E_ID(x) ((LOGMARK_EXAMPLE_ID << 16)|(x))
+
+#define LOGMARK_CNTXTSW		LOGMARK_E_ID(1)
+
+struct logdev_mark_switch {
+	struct logdev_mark_hdr hdr;
+	short pid_prev;
+	short pid_next;
+	int prev_prio;
+	int prev_static_prio;
+	int prev_normal_prio;
+	int prev_rt_prio;
+	int prev_state;
+	int next_prio;
+	int next_static_prio;
+	int next_normal_prio;
+	int next_rt_prio;
+	char prev_comm[TASK_COMM_LEN];
+	char next_comm[TASK_COMM_LEN];
+};
+
 
 /* ---------------- end of user space custom headers ---------------- */
 
@@ -65,6 +87,26 @@ static void logdev_print_hdr(int cpu,
 
 /* Place printing of traces here */
 
+static void logdev_mark_switch_print(int cpu, int size,
+				     struct logdev_mark_switch *lm)
+{
+	logdev_print_hdr(cpu, &lm->hdr);
+
+	printk("%s:%d(%d:%d:%d) -->> ",
+	       lm->prev_comm,
+	       lm->pid_prev,
+	       lm->prev_prio,
+	       lm->prev_static_prio,
+	       lm->prev_normal_prio);
+
+	printk("%s:%d(%d:%d:%d)\n",
+	       lm->next_comm,
+	       lm->pid_next,
+	       lm->next_prio,
+	       lm->next_static_prio,
+	       lm->next_normal_prio);
+}
+
 static void logdev_mark_callback(struct logdev_header *hdr,
 				 struct logdev_custom *custom,
 				 int cpu,
@@ -74,6 +116,9 @@ static void logdev_mark_callback(struct 
 
 	switch (lm->id) {
 	/* Add callbacks for traces here */
+	case LOGMARK_CNTXTSW:
+		logdev_mark_switch_print(cpu, hdr->size, rec);
+		break;
 	default:
 		printk("Unknown marker callback id %x\n",
 		       lm->id);
@@ -92,6 +137,37 @@ static void __kprobes logmark_hdr(struct
 
 /* Add tracing callback functions here */
 
+void __kprobes LDCALLER(context_switch) (struct task_struct *prev,
+					 struct task_struct *next)
+{
+	struct logdev_mark_switch lm;
+
+	/* Filter on test task */
+	/*
+	if ((strncmp(prev->comm, "sched_football", 14) != 0) &&
+	    (strncmp(next->comm, "sched_football", 14) != 0))
+		return;
+	*/
+
+	logmark_hdr(&lm.hdr, LOGMARK_CNTXTSW);
+
+	lm.pid_prev = prev->pid;
+	lm.prev_prio = prev->prio;
+	lm.prev_static_prio = prev->static_prio;
+	lm.prev_normal_prio = prev->normal_prio;
+	lm.prev_rt_prio = prev->rt_priority;
+	lm.prev_state = prev->state;
+	lm.pid_next = next->pid;
+	lm.next_prio = next->prio;
+	lm.next_static_prio = next->static_prio;
+	lm.next_normal_prio = next->normal_prio;
+	lm.next_rt_prio = next->rt_priority;
+	memcpy(lm.prev_comm, prev->comm, TASK_COMM_LEN);
+	memcpy(lm.next_comm, next->comm, TASK_COMM_LEN);
+
+	logdev_record(LOGMARK_ID_MARK, sizeof(lm),
+		      &lm, sizeof(lm), NULL);
+}
 
 static int __init logdev_tracer_init(void)
 {
Index: linux-2.6.21.5-rt20/kernel/sched.c
===================================================================
--- linux-2.6.21.5-rt20.orig/kernel/sched.c	2007-07-11 10:09:48.000000000 +0200
+++ linux-2.6.21.5-rt20/kernel/sched.c	2007-07-11 14:28:56.000000000 +0200
@@ -61,6 +61,7 @@
 #include <linux/kprobes.h>
 #include <linux/delayacct.h>
 #include <linux/reciprocal_div.h>
+#include <linux/logdev_marker.h>
 
 #include <asm/tlb.h>
 #include <asm/unistd.h>
@@ -2143,6 +2144,8 @@ context_switch(struct rq *rq, struct tas
 {
 	struct mm_struct *mm, *oldmm;
 
+	LD_MARK2(context_switch, prev, next);
+
 	prepare_task_switch(rq, next);
 	mm = next->mm;
 	oldmm = prev->active_mm;