include/linux/sched.h  |    2 +-
 include/linux/sysctl.h |    1 +
 kernel/sched.c         |   42 ++++++++++++++++++++++++++++++++++--------
 kernel/sysctl.c        |    8 ++++++++
 4 files changed, 44 insertions(+), 9 deletions(-)

Index: linux-2.6.17-rc5-ck1/include/linux/sched.h
===================================================================
--- linux-2.6.17-rc5-ck1.orig/include/linux/sched.h	2006-05-25 12:57:50.000000000 +1000
+++ linux-2.6.17-rc5-ck1/include/linux/sched.h	2006-05-25 12:57:50.000000000 +1000
@@ -202,7 +202,7 @@ extern void show_stack(struct task_struc
 
 void io_schedule(void);
 long io_schedule_timeout(long timeout);
-extern int sched_interactive;
+extern int sched_interactive, sched_compute;
 
 extern void cpu_init (void);
 extern void trap_init(void);
Index: linux-2.6.17-rc5-ck1/include/linux/sysctl.h
===================================================================
--- linux-2.6.17-rc5-ck1.orig/include/linux/sysctl.h	2006-05-25 12:57:50.000000000 +1000
+++ linux-2.6.17-rc5-ck1/include/linux/sysctl.h	2006-05-25 12:57:50.000000000 +1000
@@ -149,6 +149,7 @@ enum
 	KERN_ACPI_VIDEO_FLAGS=71, /* int: flags for setting up video after ACPI sleep */
 	KERN_IA64_UNALIGNED=72, /* int: ia64 unaligned userland trap enable */
 	KERN_INTERACTIVE=73,	/* interactive tasks can have cpu bursts */
+	KERN_COMPUTE=74,	/* adjust timeslices for a compute server */
 };
 
 
Index: linux-2.6.17-rc5-ck1/kernel/sched.c
===================================================================
--- linux-2.6.17-rc5-ck1.orig/kernel/sched.c	2006-05-25 12:57:50.000000000 +1000
+++ linux-2.6.17-rc5-ck1/kernel/sched.c	2006-05-25 12:57:50.000000000 +1000
@@ -60,8 +60,17 @@
 /*
  * sched_interactive - sysctl which allows interactive tasks to have bonus
  * raise its priority.
+ * sched_compute - sysctl which enables long timeslices and delayed preemption
+ * for compute server usage.
  */
 int sched_interactive __read_mostly = 1;
+int sched_compute __read_mostly = 0;
+
+/*
+ * CACHE_DELAY is the time preemption is delayed in sched_compute mode
+ * and is set to a nominal 10ms.
+ */
+#define CACHE_DELAY	(10 * (HZ) / 1001 + 1)
 
 /*
  * Convert user-nice values [ -20 ... 0 ... 19 ]
@@ -92,9 +101,10 @@ int sched_interactive __read_mostly = 1;
 
 /*
  * This is the time all tasks within the same priority round robin.
- * Set to a minimum of 6ms.
+ * Set to a minimum of 6ms. It is 10 times longer in compute mode.
  */
-#define RR_INTERVAL		((6 * HZ / 1001) + 1)
+#define _RR_INTERVAL		((6 * HZ / 1001) + 1)
+#define RR_INTERVAL		(_RR_INTERVAL * (1 + 9 * sched_compute))
 #define DEF_TIMESLICE		(RR_INTERVAL * 19)
 
 #define task_hot(p, now, sd) ((long long) ((now) - (p)->timestamp)	\
@@ -135,6 +145,7 @@ struct runqueue {
 	unsigned long nr_uninterruptible;
 
 	unsigned long long timestamp_last_tick;
+	unsigned short cache_ticks, preempted;
 	task_t *curr, *idle;
 	struct mm_struct *prev_mm;
 	unsigned long bitmap[BITS_TO_LONGS(MAX_PRIO + 1)];
@@ -737,7 +748,7 @@ static int effective_prio(const task_t *
 
 	best_bonus = bonus(p);
 	prio = MAX_RT_PRIO + best_bonus;
-	if (sched_interactive && !batch_task(p))
+	if (sched_interactive && !sched_compute && !batch_task(p))
 		prio -= p->bonus;
 
 	rr = rr_interval(p);
@@ -1208,12 +1219,21 @@ static inline int wake_idle(int cpu, tas
 #endif
 
 /*
- * Check to see if p preempts rq->curr and resched if it does.
+ * Check to see if p preempts rq->curr and resched if it does. In compute
+ * mode we do not preempt for at least CACHE_DELAY and set rq->preempted.
  */
-static inline void preempt(const task_t *p, runqueue_t *rq)
+static void fastcall preempt(const task_t *p, runqueue_t *rq)
 {
-	if (TASK_PREEMPTS_CURR(p, rq))
-		resched_task(rq->curr);
+	task_t *curr = rq->curr;
+
+	if (p->prio >= curr->prio)
+		return;
+	if (!sched_compute || rq->cache_ticks >= CACHE_DELAY || !p->mm ||
+	    rt_task(p) || curr == rq->idle) {
+		resched_task(curr);
+		return;
+	}
+	rq->preempted = 1;
 }
 
 /***
@@ -2669,6 +2689,11 @@ void scheduler_tick(void)
 		time_slice_expired(p, rq);
 		goto out_unlock;
 	}
+	rq->cache_ticks++;
+	if (rq->preempted && rq->cache_ticks >= CACHE_DELAY) {
+		set_tsk_need_resched(p);
+		goto out_unlock;
+	}
 	expired_balance = 0;
 out_unlock:
 	spin_unlock(&rq->lock);
@@ -2993,6 +3018,7 @@ switch_tasks:
 
 	sched_info_switch(prev, next);
 	if (likely(prev != next)) {
+		rq->preempted = rq->cache_ticks = 0;
 		next->timestamp = now;
 		rq->nr_switches++;
 		rq->curr = next;
@@ -6031,7 +6057,7 @@ void __init sched_init(void)
 
 		rq = cpu_rq(i);
 		spin_lock_init(&rq->lock);
-		rq->nr_running = 0;
+		rq->nr_running = rq->cache_ticks = rq->preempted = 0;
 
 #ifdef CONFIG_SMP
 		rq->sd = NULL;
Index: linux-2.6.17-rc5-ck1/kernel/sysctl.c
===================================================================
--- linux-2.6.17-rc5-ck1.orig/kernel/sysctl.c	2006-05-25 12:57:50.000000000 +1000
+++ linux-2.6.17-rc5-ck1/kernel/sysctl.c	2006-05-25 12:57:50.000000000 +1000
@@ -631,6 +631,14 @@ static ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+	{
+		.ctl_name	= KERN_COMPUTE,
+		.procname	= "compute",
+		.data		= &sched_compute,
+		.maxlen		= sizeof (int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
 	{
 		.ctl_name       = KERN_UNKNOWN_NMI_PANIC,