[PATCH] optional non-interactive mode for cpu scheduler

[Con Kolivas]

optional non-interactive mode for cpu scheduler


Some environments desire strict control over cpu resources based on nice
values without interactive determination.

Add a sysctl (/proc/sys/kernel/interactive) to disable dynamic priority
behaviour and interactive reinsertion.

Signed-off-by: Con Kolivas <kernel@xxxxxxxxxxx>


Index: linux-2.6.10-rc1-mm2/include/linux/sched.h
===================================================================
--- linux-2.6.10-rc1-mm2.orig/include/linux/sched.h	2004-11-02 13:20:03.000000000 +1100
+++ linux-2.6.10-rc1-mm2/include/linux/sched.h	2004-11-02 16:03:53.807209246 +1100
@@ -738,6 +738,7 @@ extern int task_prio(const task_t *p);
 extern int task_nice(const task_t *p);
 extern int task_curr(const task_t *p);
 extern int idle_cpu(int cpu);
+extern int sched_interactive;
 
 void yield(void);
 
Index: linux-2.6.10-rc1-mm2/include/linux/sysctl.h
===================================================================
--- linux-2.6.10-rc1-mm2.orig/include/linux/sysctl.h	2004-11-02 13:19:19.000000000 +1100
+++ linux-2.6.10-rc1-mm2/include/linux/sysctl.h	2004-11-02 16:07:46.071023189 +1100
@@ -134,6 +134,7 @@ enum
 	KERN_SPARC_SCONS_PWROFF=64, /* int: serial console power-off halt */
 	KERN_HZ_TIMER=65,	/* int: hz timer on or off */
 	KERN_UNKNOWN_NMI_PANIC=66, /* int: unknown nmi panic flag */
+	KERN_INTERACTIVE=67,	/* int: dynamic priorities */
 };
 
 
Index: linux-2.6.10-rc1-mm2/kernel/sched.c
===================================================================
--- linux-2.6.10-rc1-mm2.orig/kernel/sched.c	2004-11-02 14:52:51.000000000 +1100
+++ linux-2.6.10-rc1-mm2/kernel/sched.c	2004-11-02 16:13:48.419712248 +1100
@@ -150,8 +150,8 @@
 #define DELTA(p) \
 	(SCALE(TASK_NICE(p), 40, MAX_BONUS) + INTERACTIVE_DELTA)
 
-#define TASK_INTERACTIVE(p) \
-	((p)->prio <= (p)->static_prio - DELTA(p))
+#define TASK_INTERACTIVE(p) ((sched_interactive) && \
+	((p)->prio <= (p)->static_prio - DELTA(p)))
 
 #define INTERACTIVE_SLEEP(p) \
 	(JIFFIES_TO_NS(MAX_SLEEP_AVG * \
@@ -602,6 +602,13 @@ static inline void enqueue_task_head(str
 }
 
 /*
+ * This is a sysctl which allows dynamic priorities to be applied based on
+ * interactive behaviour, and selective interactive reinsertion into the
+ * active array despite timeslice expiration.
+ */
+int sched_interactive = 1;
+
+/*
  * effective_prio - return the priority that is based on the static
  * priority but is modified by bonuses/penalties.
  *
@@ -622,6 +629,10 @@ static int effective_prio(task_t *p)
 	if (rt_task(p))
 		return p->prio;
 
+	/* Dynamic priorities are not used with interactive mode off */
+	if (!sched_interactive)
+		return p->static_prio;
+
 	bonus = CURRENT_BONUS(p) - MAX_BONUS / 2;
 
 	prio = p->static_prio - bonus;
Index: linux-2.6.10-rc1-mm2/kernel/sysctl.c
===================================================================
--- linux-2.6.10-rc1-mm2.orig/kernel/sysctl.c	2004-11-02 13:19:19.000000000 +1100
+++ linux-2.6.10-rc1-mm2/kernel/sysctl.c	2004-11-02 16:06:27.621555227 +1100
@@ -624,6 +624,14 @@ static ctl_table kern_table[] = {
 		.proc_handler   = &proc_unknown_nmi_panic,
 	},
 #endif
+	{
+		.ctl_name	= KERN_INTERACTIVE,
+		.procname	= "interactive",
+		.data		= &sched_interactive,
+		.maxlen		= sizeof (int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 	{ .ctl_name = 0 }
 };

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