Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b2be5e96dc0b5a179cf4cb98e65cfb605752ca26
Commit: b2be5e96dc0b5a179cf4cb98e65cfb605752ca26
Parent: 2cb8600e6be4281e381d39e44de4359e46333e23
Author: Peter Zijlstra <[EMAIL PROTECTED]>
AuthorDate: Fri Nov 9 22:39:37 2007 +0100
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Fri Nov 9 22:39:37 2007 +0100
sched: reintroduce the sched_min_granularity tunable
we lost the sched_min_granularity tunable to a clever optimization
that uses the sched_latency/min_granularity ratio - but the ratio
is quite unintuitive to users and can also crash the kernel if the
ratio is set to 0. So reintroduce the min_granularity tunable,
while keeping the ratio maintained internally.
no functionality changed.
[ [EMAIL PROTECTED]: some fixlets. ]
Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
include/linux/sched.h | 6 +++++-
kernel/sched_debug.c | 2 +-
kernel/sched_fair.c | 35 ++++++++++++++++++++++++++++-------
kernel/sysctl.c | 11 +++++++----
4 files changed, 41 insertions(+), 13 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 155d743..5457b62 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1460,12 +1460,16 @@ extern void sched_idle_next(void);
#ifdef CONFIG_SCHED_DEBUG
extern unsigned int sysctl_sched_latency;
-extern unsigned int sysctl_sched_nr_latency;
+extern unsigned int sysctl_sched_min_granularity;
extern unsigned int sysctl_sched_wakeup_granularity;
extern unsigned int sysctl_sched_batch_wakeup_granularity;
extern unsigned int sysctl_sched_child_runs_first;
extern unsigned int sysctl_sched_features;
extern unsigned int sysctl_sched_migration_cost;
+
+int sched_nr_latency_handler(struct ctl_table *table, int write,
+ struct file *file, void __user *buffer, size_t *length,
+ loff_t *ppos);
#endif
extern unsigned int sysctl_sched_compat_yield;
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 415e5c3..ca198a7 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -211,7 +211,7 @@ static int sched_debug_show(struct seq_file *m, void *v)
#define PN(x) \
SEQ_printf(m, " .%-40s: %Ld.%06ld\n", #x, SPLIT_NS(x))
PN(sysctl_sched_latency);
- PN(sysctl_sched_nr_latency);
+ PN(sysctl_sched_min_granularity);
PN(sysctl_sched_wakeup_granularity);
PN(sysctl_sched_batch_wakeup_granularity);
PN(sysctl_sched_child_runs_first);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 8763bee..c495dcf 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -35,16 +35,21 @@
const_debug unsigned int sysctl_sched_latency = 20000000ULL;
/*
- * After fork, child runs first. (default) If set to 0 then
- * parent will (try to) run first.
+ * Minimal preemption granularity for CPU-bound tasks:
+ * (default: 1 msec, units: nanoseconds)
*/
-const_debug unsigned int sysctl_sched_child_runs_first = 1;
+const_debug unsigned int sysctl_sched_min_granularity = 1000000ULL;
/*
- * Minimal preemption granularity for CPU-bound tasks:
- * (default: 2 msec, units: nanoseconds)
+ * is kept at sysctl_sched_latency / sysctl_sched_min_granularity
*/
-const_debug unsigned int sysctl_sched_nr_latency = 20;
+const_debug unsigned int sched_nr_latency = 20;
+
+/*
+ * After fork, child runs first. (default) If set to 0 then
+ * parent will (try to) run first.
+ */
+const_debug unsigned int sysctl_sched_child_runs_first = 1;
/*
* sys_sched_yield() compat mode
@@ -212,6 +217,22 @@ static inline struct sched_entity
*__pick_last_entity(struct cfs_rq *cfs_rq)
* Scheduling class statistics methods:
*/
+#ifdef CONFIG_SCHED_DEBUG
+int sched_nr_latency_handler(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+
+ if (ret || !write)
+ return ret;
+
+ sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
+ sysctl_sched_min_granularity);
+
+ return 0;
+}
+#endif
/*
* The idea is to set a period in which each task runs once.
@@ -224,7 +245,7 @@ static inline struct sched_entity
*__pick_last_entity(struct cfs_rq *cfs_rq)
static u64 __sched_period(unsigned long nr_running)
{
u64 period = sysctl_sched_latency;
- unsigned long nr_latency = sysctl_sched_nr_latency;
+ unsigned long nr_latency = sched_nr_latency;
if (unlikely(nr_running > nr_latency)) {
period *= nr_running;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3b4efbe..6e3b63c 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -235,11 +235,14 @@ static struct ctl_table kern_table[] = {
#ifdef CONFIG_SCHED_DEBUG
{
.ctl_name = CTL_UNNUMBERED,
- .procname = "sched_nr_latency",
- .data = &sysctl_sched_nr_latency,
+ .procname = "sched_min_granularity_ns",
+ .data = &sysctl_sched_min_granularity,
.maxlen = sizeof(unsigned int),
.mode = 0644,
- .proc_handler = &proc_dointvec,
+ .proc_handler = &sched_nr_latency_handler,
+ .strategy = &sysctl_intvec,
+ .extra1 = &min_sched_granularity_ns,
+ .extra2 = &max_sched_granularity_ns,
},
{
.ctl_name = CTL_UNNUMBERED,
@@ -247,7 +250,7 @@ static struct ctl_table kern_table[] = {
.data = &sysctl_sched_latency,
.maxlen = sizeof(unsigned int),
.mode = 0644,
- .proc_handler = &proc_dointvec_minmax,
+ .proc_handler = &sched_nr_latency_handler,
.strategy = &sysctl_intvec,
.extra1 = &min_sched_granularity_ns,
.extra2 = &max_sched_granularity_ns,
-
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