From: John Hawkes <hawkes@google.engr.sgi.com>

Here is a patch against 2.6.1-mm3 that I believe restores the "sched_clock
fix" from -mm2.  I've also fixed the declaration of timestamp_last_tick to
be "unsigned long long", to match task->timestamp and sched_clock().



---

 25-akpm/kernel/sched.c |   16 ++++++----------
 1 files changed, 6 insertions(+), 10 deletions(-)

diff -puN kernel/sched.c~sched-clock-fixes kernel/sched.c
--- 25/kernel/sched.c~sched-clock-fixes	Thu Mar 11 14:33:25 2004
+++ 25-akpm/kernel/sched.c	Thu Mar 11 14:33:25 2004
@@ -204,8 +204,8 @@ struct prio_array {
 struct runqueue {
 	spinlock_t lock;
 	unsigned long long nr_switches;
-	unsigned long nr_running, expired_timestamp, nr_uninterruptible,
-		timestamp_last_tick;
+	unsigned long nr_running, expired_timestamp, nr_uninterruptible;
+	unsigned long long timestamp_last_tick;
 	task_t *curr, *idle;
 	struct mm_struct *prev_mm;
 	prio_array_t *active, *expired, arrays[2];
@@ -1252,8 +1252,7 @@ static inline void pull_task(runqueue_t 
  */
 static inline
 int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
-		unsigned long long now, struct sched_domain *domain,
-		enum idle_type idle)
+		struct sched_domain *domain, enum idle_type idle)
 {
 	/*
 	 * We do not migrate tasks that are:
@@ -1269,8 +1268,8 @@ int can_migrate_task(task_t *p, runqueue
 	/* Aggressive migration if we've failed balancing */
 	if (idle == NEWLY_IDLE ||
 			domain->nr_balance_failed < domain->cache_nice_tries) {
-		unsigned long long delta = now - p->timestamp;
-		if (delta < domain->cache_hot_time)
+		if ((rq->timestamp_last_tick - p->timestamp)
+						< domain->cache_hot_time)
 			return 0;
 	}
 
@@ -1288,7 +1287,6 @@ static int move_tasks(runqueue_t *this_r
 			unsigned long max_nr_move, struct sched_domain *domain,
 			enum idle_type idle)
 {
-	unsigned long long now;
 	int idx;
 	int pulled = 0;
 	prio_array_t *array, *dst_array;
@@ -1298,8 +1296,6 @@ static int move_tasks(runqueue_t *this_r
 	if (max_nr_move <= 0 || busiest->nr_running <= 1)
 		goto out;
 
-	now = sched_clock();
-
 	/*
 	 * We first consider expired tasks. Those will likely not be
 	 * executed in the near future, and they are most likely to
@@ -1338,7 +1334,7 @@ skip_queue:
 
 	curr = curr->prev;
 
-	if (!can_migrate_task(tmp, busiest, this_cpu, now, domain, idle)) {
+	if (!can_migrate_task(tmp, busiest, this_cpu, domain, idle)) {
 		if (curr != head)
 			goto skip_queue;
 		idx++;

_