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Message-ID: <20060903132802.GD10120@plankton.ifup.org>
Date: Sun, 3 Sep 2006 08:28:02 -0500
From: Brandon Philips <brandon@...p.org>
To: mingo@...e.hu, rml@...h9.net
Cc: "Brandon D. Philips" <brandon@...p.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH] Export CPU Scheduler Tunables via DebugFS
This patch exports the CPU scheduler tunables via DebugFS.
philips@...nkton:~$ ls /debug/cpu-scheduler/
child_penalty interactive_delta min_timeslice prio_bonus_ratio
def_timeslice max_bonus on_runqueue_weight starvation_limit
exit_weight max_sleep_avg parent_penalty
It is similiar to the patches by Robert Love and Ingo Molnar that were
available for the 2.5 series: http://kerneltrap.org/node/525/1938
The goal remains the same: offer a simple way for _developers_ to tune and
debug the scheduler.
Perhaps someone could even automate the testing of different values[1] under
different workloads[2].
[1] http://meikon.homeip.net/extras/papers/linux-2.5-scheduler-analysis.pdf
[2] http://test.kernel.org/autotest/QuickStart
Signed-off-by: Brandon D. Philips <brandon@...p.org>
---
kernel/sched.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++------
lib/Kconfig.debug | 8 +++
2 files changed, 112 insertions(+), 11 deletions(-)
Index: linux-rc/kernel/sched.c
===================================================================
--- linux-rc.orig/kernel/sched.c
+++ linux-rc/kernel/sched.c
@@ -52,6 +52,7 @@
#include <linux/acct.h>
#include <linux/kprobes.h>
#include <linux/delayacct.h>
+#include <linux/debugfs.h>
#include <asm/tlb.h>
#include <asm/unistd.h>
@@ -87,17 +88,60 @@
* default timeslice is 100 msecs, maximum timeslice is 800 msecs.
* Timeslices get refilled after they expire.
*/
-#define MIN_TIMESLICE max(5 * HZ / 1000, 1)
-#define DEF_TIMESLICE (100 * HZ / 1000)
-#define ON_RUNQUEUE_WEIGHT 30
-#define CHILD_PENALTY 95
-#define PARENT_PENALTY 100
-#define EXIT_WEIGHT 3
-#define PRIO_BONUS_RATIO 25
-#define MAX_BONUS (MAX_USER_PRIO * PRIO_BONUS_RATIO / 100)
-#define INTERACTIVE_DELTA 2
-#define MAX_SLEEP_AVG (DEF_TIMESLICE * MAX_BONUS)
-#define STARVATION_LIMIT (MAX_SLEEP_AVG)
+#define DEFAULT_MIN_TIMESLICE max(5 * HZ / 1000, 1)
+#define DEFAULT_DEF_TIMESLICE (100 * HZ / 1000)
+#define DEFAULT_ON_RUNQUEUE_WEIGHT 30
+#define DEFAULT_CHILD_PENALTY 95
+#define DEFAULT_PARENT_PENALTY 100
+#define DEFAULT_EXIT_WEIGHT 3
+#define DEFAULT_PRIO_BONUS_RATIO 25
+#define DEFAULT_MAX_BONUS (MAX_USER_PRIO * DEFAULT_PRIO_BONUS_RATIO / 100)
+#define DEFAULT_INTERACTIVE_DELTA 2
+#define DEFAULT_MAX_SLEEP_AVG (DEFAULT_DEF_TIMESLICE * DEFAULT_MAX_BONUS)
+#define DEFAULT_STARVATION_LIMIT (DEFAULT_MAX_SLEEP_AVG)
+#define DEFAULT_NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(DEFAULT_MAX_SLEEP_AVG))
+
+/*
+ * Simply use the static definitions if we are not exporting tunables via
+ * DebugFS for runtime tuning.
+ */
+#ifndef CONFIG_DEBUGFS_SCHED
+#define MIN_TIMESLICE DEFAULT_MIN_TIMESLICE
+#define DEF_TIMESLICE DEFAULT_DEF_TIMESLICE
+#define ON_RUNQUEUE_WEIGHT DEFAULT_ON_RUNQUEUE_WEIGHT
+#define CHILD_PENALTY DEFAULT_CHILD_PENALTY
+#define PARENT_PENALTY DEFAULT_PARENT_PENALTY
+#define EXIT_WEIGHT DEFAULT_EXIT_WEIGHT
+#define PRIO_BONUS_RATIO DEFAULT_PRIO_BONUS_RATIO
+#define MAX_BONUS DEFAULT_MAX_BONUS
+#define INTERACTIVE_DELTA DEFAULT_INTERACTIVE_DELTA
+#define MAX_SLEEP_AVG DEFAULT_MAX_SLEEP_AVG
+#define STARVATION_LIMIT DEFAULT_STARVATION_LIMIT
+#else
+int min_timeslice;
+#define MIN_TIMESLICE (min_timeslice)
+int def_timeslice;
+#define DEF_TIMESLICE (def_timeslice)
+int on_runqueue_weight;
+#define ON_RUNQUEUE_WEIGHT (on_runqueue_weight)
+int child_penalty;
+#define CHILD_PENALTY (child_penalty)
+int parent_penalty;
+#define PARENT_PENALTY (parent_penalty)
+int exit_weight;
+#define EXIT_WEIGHT (exit_weight)
+int prio_bonus_ratio;
+#define PRIO_BONUS_RATIO (prio_bonus_ratio)
+int max_bonus;
+#define MAX_BONUS (max_bonus)
+int interactive_delta;
+#define INTERACTIVE_DELTA (interactive_delta)
+int max_sleep_avg;
+#define MAX_SLEEP_AVG (max_sleep_avg)
+int starvation_limit;
+#define STARVATION_LIMIT (starvation_limit)
+#endif
+
#define NS_MAX_SLEEP_AVG (JIFFIES_TO_NS(MAX_SLEEP_AVG))
/*
@@ -6725,10 +6769,59 @@ int in_sched_functions(unsigned long add
&& addr < (unsigned long)__sched_text_end);
}
+#ifdef CONFIG_DEBUGFS_SCHED
+
+#define debugfs_sched_create(name, parent) \
+debugfs_create_u32(#name, 0644, parent, &name)
+
+int __init init_debugfs(void)
+{
+ struct dentry * root;
+
+ if ((root = debugfs_create_dir("cpu-scheduler", NULL)) == NULL)
+ goto err_root;
+
+ debugfs_sched_create(min_timeslice, root);
+ debugfs_sched_create(def_timeslice, root);
+ debugfs_sched_create(on_runqueue_weight, root);
+ debugfs_sched_create(child_penalty, root);
+ debugfs_sched_create(parent_penalty, root);
+ debugfs_sched_create(exit_weight, root);
+ debugfs_sched_create(prio_bonus_ratio, root);
+ debugfs_sched_create(max_bonus, root);
+ debugfs_sched_create(interactive_delta , root);
+ debugfs_sched_create(max_sleep_avg, root);
+ debugfs_sched_create(starvation_limit, root);
+
+err_root:
+ return 0;
+}
+postcore_initcall(init_debugfs);
+
+void __init init_tunables(void)
+{
+ min_timeslice = DEFAULT_MIN_TIMESLICE;
+ def_timeslice = DEFAULT_DEF_TIMESLICE;
+ on_runqueue_weight = DEFAULT_ON_RUNQUEUE_WEIGHT;
+ child_penalty = DEFAULT_CHILD_PENALTY;
+ parent_penalty = DEFAULT_PARENT_PENALTY;
+ exit_weight = DEFAULT_EXIT_WEIGHT;
+ prio_bonus_ratio = DEFAULT_PRIO_BONUS_RATIO;
+ max_bonus = DEFAULT_MAX_BONUS;
+ interactive_delta = DEFAULT_INTERACTIVE_DELTA;
+ max_sleep_avg = DEFAULT_MAX_SLEEP_AVG;
+ starvation_limit = DEFAULT_STARVATION_LIMIT;
+}
+#endif
+
void __init sched_init(void)
{
int i, j, k;
+#ifdef CONFIG_DEBUGFS_SCHED
+ init_tunables();
+#endif
+
for_each_possible_cpu(i) {
struct prio_array *array;
struct rq *rq;
Index: linux-rc/lib/Kconfig.debug
===================================================================
--- linux-rc.orig/lib/Kconfig.debug
+++ linux-rc/lib/Kconfig.debug
@@ -93,6 +93,14 @@ config SCHEDSTATS
application, you can say N to avoid the very slight overhead
this adds.
+config DEBUGFS_SCHED
+ bool "Export CPU Scheduler Tunables"
+ depends on DEBUG_KERNEL && DEBUG_FS
+ help
+ If you say Y here, CPU Scheduler tuning knobs will be available via
+ debugfs in /debug/cpu-scheduler/. Note: No sanity checking is done
+ on the values.
+
config DEBUG_SLAB
bool "Debug slab memory allocations"
depends on DEBUG_KERNEL && SLAB
--
--
VGER BF report: H 1.49591e-07
-
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