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Subject[tip:sched/core] sched: Untangle cpu-load and timekeeping code
Commit-ID:  18a57c3b43781ea83c3bb21c3add84ba890d5fb3
Gitweb: http://git.kernel.org/tip/18a57c3b43781ea83c3bb21c3add84ba890d5fb3
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Tue, 25 Jan 2011 11:30:35 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 26 Jan 2011 12:33:23 +0100

sched: Untangle cpu-load and timekeeping code

Remove the calc_global_load() call from the timekeeping code and make
it local to the scheduler.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/sched.h | 2 --
kernel/sched.c | 22 ++++++++++++++++------
kernel/timer.c | 1 -
3 files changed, 16 insertions(+), 9 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0542774..738ec15 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -142,8 +142,6 @@ extern unsigned long nr_iowait_cpu(int cpu);
extern unsigned long this_cpu_load(void);


-extern void calc_global_load(unsigned long ticks);
-
extern unsigned long get_parent_ip(unsigned long addr);

struct seq_file;
diff --git a/kernel/sched.c b/kernel/sched.c
index 78fa753..3fc5749 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3192,7 +3192,7 @@ calc_load_n(unsigned long load, unsigned long exp,
* Once we've updated the global active value, we need to apply the exponential
* weights adjusted to the number of cycles missed.
*/
-static void calc_global_nohz(unsigned long ticks)
+static void calc_global_nohz(void)
{
long delta, active, n;

@@ -3212,8 +3212,9 @@ static void calc_global_nohz(unsigned long ticks)
/*
* If we were idle for multiple load cycles, apply them.
*/
- if (ticks >= LOAD_FREQ) {
- n = ticks / LOAD_FREQ;
+ delta = jiffies - calc_load_update - 10;
+ if (delta >= LOAD_FREQ) {
+ n = delta / LOAD_FREQ;

active = atomic_long_read(&calc_load_tasks);
active = active > 0 ? active * FIXED_1 : 0;
@@ -3246,7 +3247,7 @@ static inline long calc_load_fold_idle(void)
return 0;
}

-static void calc_global_nohz(unsigned long ticks)
+static void calc_global_nohz(void)
{
}
#endif
@@ -3266,15 +3267,20 @@ void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
loads[2] = (avenrun[2] + offset) << shift;
}

+static void calc_global_load(unsigned long __data);
+
+static struct timer_list global_load_timer =
+ TIMER_DEFERRED_INITIALIZER(calc_global_load, 0, 0);
+
/*
* calc_load - update the avenrun load estimates 10 ticks after the
* CPUs have updated calc_load_tasks.
*/
-void calc_global_load(unsigned long ticks)
+static void calc_global_load(unsigned long __data)
{
long active;

- calc_global_nohz(ticks);
+ calc_global_nohz();

if (time_before(jiffies, calc_load_update + 10))
return;
@@ -3287,6 +3293,7 @@ void calc_global_load(unsigned long ticks)
avenrun[2] = calc_load(avenrun[2], EXP_15, active);

calc_load_update += LOAD_FREQ;
+ mod_timer(&global_load_timer, calc_load_update + 10);
}

/*
@@ -7898,11 +7905,13 @@ void __init sched_init_smp(void)
free_cpumask_var(non_isolated_cpus);

init_sched_rt_class();
+ mod_timer(&global_load_timer, calc_load_update + 10);
}
#else
void __init sched_init_smp(void)
{
sched_init_granularity();
+ mod_timer(&global_load_timer, calc_load_update + 10);
}
#endif /* CONFIG_SMP */

@@ -8172,6 +8181,7 @@ void __init sched_init(void)
init_idle(current, smp_processor_id());

calc_load_update = jiffies + LOAD_FREQ;
+ set_timer_slack(&global_load_timer, 0);

/*
* During early bootup we pretend to be a normal task:
diff --git a/kernel/timer.c b/kernel/timer.c
index 43ca993..afdc13b 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1303,7 +1303,6 @@ void do_timer(unsigned long ticks)
{
jiffies_64 += ticks;
update_wall_time();
- calc_global_load(ticks);
}

#ifdef __ARCH_WANT_SYS_ALARM

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