(2-2) governors for 60-bk

Here is the modified schedule tunables patch

schedule_tunables-C4

Ed Tomlinson

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher. # This patch includes the following deltas:
# ChangeSet 1.963 -> 1.964
# kernel/sysctl.c 1.39 -> 1.40
# Documentation/filesystems/proc.txt 1.13 -> 1.14
# include/linux/sysctl.h 1.40 -> 1.41
# kernel/sched.c 1.156 -> 1.157
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/01/25 [email protected] 1.964

# add scheduler tunables including governors and NUMA knobs
# --------------------------------------------
#
diff -Nru a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
--- a/Documentation/filesystems/proc.txt	Sat Jan 25 11:07:17 2003
+++ b/Documentation/filesystems/proc.txt	Sat Jan 25 11:07:17 2003
@@ -37,6 +37,7 @@
   2.8	/proc/sys/net/ipv4 - IPV4 settings
   2.9	Appletalk
   2.10	IPX
+  2.11  /proc/sys/sched - scheduler tunables

------------------------------------------------------------------------------
Preface
@@ -1662,6 +1663,113 @@
The /proc/net/ipx_route table holds a list of IPX routes. For each route it gives the destination network, the router node (or Directly) and the network address of the router (or Connected) for internal networks.
+
+2.11 /proc/sys/sched - scheduler tunables
+-----------------------------------------
+
+Useful knobs for tuning the scheduler live in /proc/sys/sched.
+
+child_penalty
+-------------
+
+Percentage of the parent's sleep_avg that children inherit. sleep_avg is +a running average of the time a process spends sleeping. Tasks with high +sleep_avg values are considered interactive and given a higher dynamic +priority and a larger timeslice. You typically want this some value just +under 100.
+
+exit_weight
+-----------
+
+When a CPU hog task exits, its parent's sleep_avg is reduced by a factor of +exit_weight against the exiting task's sleep_avg.
+
+interactive_delta
+-----------------
+
+If a task is "interactive" it is reinserted into the active array after it +has expired its timeslice, instead of being inserted into the expired array. +How "interactive" a task must be in order to be deemed interactive is a +function of its nice value. This interactive limit is scaled linearly by nice +value and is offset by the interactive_delta.
+
+max_sleep_avg
+-------------
+
+max_sleep_avg is the largest value (in ms) stored for a task's running sleep +average. The larger this value, the longer a task needs to sleep to be +considered interactive (maximum interactive bonus is a function of +max_sleep_avg).
+
+max_timeslice
+-------------
+
+Maximum timeslice, in milliseconds. This is the value given to tasks of the +highest dynamic priority.
+
+min_timeslice
+-------------
+
+Minimum timeslice, in milliseconds. This is the value given to tasks of the +lowest dynamic priority. Every task gets at least this slice of the processor +per array switch.
+
+parent_penalty
+--------------
+
+Percentage of the parent's sleep_avg that it retains across a fork(). +sleep_avg is a running average of the time a process spends sleeping. Tasks +with high sleep_avg values are considered interactive and given a higher +dynamic priority and a larger timeslice. Normally, this value is 100 and thus +task's retain their sleep_avg on fork. If you want to punish interactive +tasks for forking, set this below 100.
+
+prio_bonus_ratio
+----------------
+
+Middle percentage of the priority range that tasks can receive as a dynamic +priority. The default value of 25% ensures that nice values at the +extremes are still enforced. For example, nice +19 interactive tasks will +never be able to preempt a nice 0 CPU hog. Setting this higher will increase +the size of the priority range the tasks can receive as a bonus. Setting +this lower will decrease this range, making the interactivity bonus less +apparent and user nice values more applicable.
+
+starvation_limit
+----------------
+
+Sufficiently interactive tasks are reinserted into the active array when they +run out of timeslice. Normally, tasks are inserted into the expired array. +Reinserting interactive tasks into the active array allows them to remain +runnable, which is important to interactive performance. This could starve +expired tasks, however, since the interactive task could prevent the array +switch. To prevent starving the tasks on the expired array for too long. the +starvation_limit is the longest (in ms) we will let the expired array starve +at the expense of reinserting interactive tasks back into active. Higher +values here give more preferance to running interactive tasks, at the expense +of expired tasks. Lower values provide more fair scheduling behavior, at the +expense of interactivity. The units are in milliseconds.
+
+thread_governor
+---------------
+
+When the number of active threads in a threadgroup exceeds the limit reduce the +timeslices of active members by thread_governor / active_threads_in_group. In +the NUMA case the limits are per node. The thread_governor is applied before +the user_governor. Units are number of threads times 10.
+
+user_governor
+-------------
+
+When the number of active threads of user exceeds the limit reduce the timeslices +of the user's active processes by user_governor / active_threads_of_user. In the +NUMA case the limits are per node. Units are number of threads times 10. +
+node_threshold
+--------------
+
+Consider NUMA nodes imbalanced when there is a difference of more than this +percentage.

------------------------------------------------------------------------------
Summary

diff -Nru a/include/linux/sysctl.h b/include/linux/sysctl.h
@@ -66,7 +66,8 @@
 	CTL_DEV=7,		/* Devices */
 	CTL_BUS=8,		/* Busses */
 	CTL_ABI=9,		/* Binary emulation */
-	CTL_CPU=10		/* CPU stuff (speed scaling, etc) */
+	CTL_CPU=10,		/* CPU stuff (speed scaling, etc) */
+	CTL_SCHED=11,		/* scheduler tunables */
 };
 
 /* CTL_BUS names: */

@@ -157,6 +158,21 @@
 	VM_LOWER_ZONE_PROTECTION=20,/* Amount of protection of lower zones */
 };
 
+/* Tunable scheduler parameters in /proc/sys/sched/ */
+enum {
+	SCHED_MIN_TIMESLICE=1,		/* minimum process timeslice */
+	SCHED_MAX_TIMESLICE=2,		/* maximum process timeslice */
+	SCHED_CHILD_PENALTY=3,		/* penalty on fork to child */
+	SCHED_PARENT_PENALTY=4,		/* penalty on fork to parent */
+	SCHED_EXIT_WEIGHT=5,		/* penalty to parent of CPU hog child */
+	SCHED_PRIO_BONUS_RATIO=6,	/* percent of max prio given as bonus */
+	SCHED_INTERACTIVE_DELTA=7,	/* delta used to scale interactivity */
+	SCHED_MAX_SLEEP_AVG=8,		/* maximum sleep avg attainable */
+	SCHED_STARVATION_LIMIT=9,	/* no re-active if expired is starved */
+	SCHED_THREAD_GOVERNOR=10,	/* govern threadgroups when needed */
+	SCHED_USER_GOVERNOR=11,		/* govern users when needed  */
+	SCHED_NODE_THRESHOLD=12,	/* NUMA imbalance threshold */
+};
 
 /* CTL_NET names: */
 enum

diff -Nru a/kernel/sched.c b/kernel/sched.c
@@ -57,19 +57,35 @@
  * Minimum timeslice is 10 msecs, default timeslice is 150 msecs,
  * maximum timeslice is 300 msecs. Timeslices get refilled after
  * they expire.
+ *
+ * They are configurable via /proc/sys/sched
  */
-#define MIN_TIMESLICE		( 10 * HZ / 1000)
-#define MAX_TIMESLICE		(300 * HZ / 1000)
-#define CHILD_PENALTY		95
-#define PARENT_PENALTY		100
-#define THREAD_GOVERNOR		15	/* allow threads groups 1.5 full timeslices */
-#define USER_GOVERNOR		300	/* allow user 30 full timeslices */
-#define EXIT_WEIGHT		3
-#define PRIO_BONUS_RATIO	25
-#define INTERACTIVE_DELTA	2
-#define MAX_SLEEP_AVG		(2*HZ)
-#define STARVATION_LIMIT	(2*HZ)
-#define NODE_THRESHOLD          125
+
+int min_timeslice = (10 * HZ) / 1000;
+int max_timeslice = (300 * HZ) / 1000;
+int child_penalty = 95;
+int parent_penalty = 100;
+int thread_governor = 15;
+int user_governor = 300;
+int exit_weight = 3;
+int prio_bonus_ratio = 25;
+int interactive_delta = 2;
+int max_sleep_avg = 2 * HZ;
+int starvation_limit = 2 * HZ;
+int node_threshold = 125;
+
+#define MIN_TIMESLICE		(min_timeslice)
+#define MAX_TIMESLICE		(max_timeslice)
+#define CHILD_PENALTY		(child_penalty)
+#define PARENT_PENALTY		(parent_penalty)
+#define THREAD_GOVERNOR		(thread_governor)
+#define USER_GOVERNOR		(user_governor)
+#define EXIT_WEIGHT		(exit_weight)
+#define PRIO_BONUS_RATIO	(prio_bonus_ratio)
+#define INTERACTIVE_DELTA	(interactive_delta)
+#define MAX_SLEEP_AVG		(max_sleep_avg)
+#define STARVATION_LIMIT	(starvation_limit)
+#define NODE_THRESHOLD		(node_threshold)
 
 /*
  * If a task is 'interactive' then we reinsert it in the active