add /proc/sys/kernel/cache_decay_ticks

[David Mosberger]

/proc/sys/kernel/cache_decay_ticks allows runtime tuning of the
scheduler.  The earlier patch collided with the C99-ification of the
file, so here is a retransmit.

	--david

diff -Nru a/include/linux/sysctl.h b/include/linux/sysctl.h
--- a/include/linux/sysctl.h	Wed Jun 18 13:32:49 2003
+++ b/include/linux/sysctl.h	Wed Jun 18 13:32:49 2003
@@ -130,6 +130,7 @@
 	KERN_PIDMAX=55,		/* int: PID # limit */
   	KERN_CORE_PATTERN=56,	/* string: pattern for core-file names */
 	KERN_PANIC_ON_OOPS=57,  /* int: whether we will panic on an oops */
+	KERN_CACHEDECAYTICKS=58, /* ulong: value for cache_decay_ticks (EXPERIMENTAL!) */
 };
 
 
diff -Nru a/kernel/sysctl.c b/kernel/sysctl.c
--- a/kernel/sysctl.c	Wed Jun 18 13:32:49 2003
+++ b/kernel/sysctl.c	Wed Jun 18 13:32:49 2003
@@ -551,6 +551,16 @@
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+#ifdef CONFIG_SMP
+	{
+		.ctl_name	= KERN_CACHEDECAYTICKS,
+		.procname	= "cache_decay_ticks",
+		.data		= &cache_decay_ticks,
+		.maxlen		= sizeof(cache_decay_ticks),
+		.mode		= 0644,
+		.proc_handler	= &proc_doulongvec_minmax,
+	},
+#endif
 	{ .ctl_name = 0 }
 };