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SubjectRe: [PATCH 01/18] move do_timer() from kernel/timer.c into kernel/time/timekeeping.c
On Wed, Jan 26, 2011 at 11:03:56AM +0100, Peter Zijlstra wrote:
> On Wed, 2011-01-26 at 13:56 +0800, Yong Zhang wrote:
>
>
> > +static __init void start_calc_global_timer()
> > +{
> > + calc_load_update = jiffies + LOAD_FREQ;
>
> That should really be done where it was done in sched_init(), otherwise
> rq->calc_load_update and this get out of sync.

Ah, yes. Will update.

---
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [PATCH V2] sched: Move the calc_global_load() call into the scheduler

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>
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
---
include/linux/sched.h | 2 --
kernel/sched.c | 31 ++++++++++++++++++++++---------
kernel/timer.c | 1 -
3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d747f94..f224dcc 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 18d38e4..7bbc743 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3159,7 +3159,7 @@ 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;

@@ -3179,8 +3179,9 @@ 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;
@@ -3213,7 +3214,7 @@ 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
@@ -3233,18 +3234,26 @@ 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);
+
+static __init void start_calc_global_timer(void)
+{
+ set_timer_slack(&global_load_timer, 0);
+ mod_timer(&global_load_timer, calc_load_update + 10);
+}
+
/*
* 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);
-
- if (time_before(jiffies, calc_load_update + 10))
- return;
+ calc_global_nohz();

active = atomic_long_read(&calc_load_tasks);
active = active > 0 ? active * FIXED_1 : 0;
@@ -3254,6 +3263,7 @@ 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);
}

/*
@@ -7741,6 +7751,8 @@ void __init sched_init_smp(void)
{
cpumask_var_t non_isolated_cpus;

+ start_calc_global_timer();
+
alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL);
alloc_cpumask_var(&fallback_doms, GFP_KERNEL);

@@ -7777,6 +7789,7 @@ void __init sched_init_smp(void)
#else
void __init sched_init_smp(void)
{
+ start_calc_global_timer();
sched_init_granularity();
}
#endif /* CONFIG_SMP */
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
--
1.7.1


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