Commit-ID: 525705d15e63b7455977408e4601e76e6bc41524
Gitweb: http://git.kernel.org/tip/525705d15e63b7455977408e4601e76e6bc41524
Author: Byungchul Park <byungchul.park@xxxxxxx>
AuthorDate: Tue, 10 Nov 2015 09:36:02 +0900
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 23 Nov 2015 09:37:53 +0100
sched/fair: Consider missed ticks in NOHZ_FULL in update_cpu_load_nohz()
Usually the tick can be stopped for an idle CPU in NOHZ. However in NOHZ_FULL
mode, a non-idle CPU's tick can also be stopped. However, update_cpu_load_nohz()
does not consider the case a non-idle CPU's tick has been stopped at all.
This patch makes the update_cpu_load_nohz() know if the calling path comes
from NOHZ_FULL or idle NOHZ.
Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1447115762-19734-3-git-send-email-byungchul.park@xxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/sched.h | 4 ++--
kernel/sched/fair.c | 10 ++++++----
kernel/time/tick-sched.c | 8 ++++----
3 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index edad7a4..f425aac 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -177,9 +177,9 @@ extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load);
extern void calc_global_load(unsigned long ticks);
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
-extern void update_cpu_load_nohz(void);
+extern void update_cpu_load_nohz(int active);
#else
-static inline void update_cpu_load_nohz(void) { }
+static inline void update_cpu_load_nohz(int active) { }
#endif
extern unsigned long get_parent_ip(unsigned long addr);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 404006a..309b1d5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4397,10 +4397,11 @@ static void update_idle_cpu_load(struct rq *this_rq)
/*
* Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
*/
-void update_cpu_load_nohz(void)
+void update_cpu_load_nohz(int active)
{
struct rq *this_rq = this_rq();
unsigned long curr_jiffies = READ_ONCE(jiffies);
+ unsigned long load = active ? weighted_cpuload(cpu_of(this_rq)) : 0;
unsigned long pending_updates;
if (curr_jiffies == this_rq->last_load_update_tick)
@@ -4411,10 +4412,11 @@ void update_cpu_load_nohz(void)
if (pending_updates) {
this_rq->last_load_update_tick = curr_jiffies;
/*
- * We were idle, this means load 0, the current load might be
- * !0 due to remote wakeups and the sort.
+ * In the regular NOHZ case, we were idle, this means load 0.
+ * In the NOHZ_FULL case, we were non-idle, we should consider
+ * its weighted load.
*/
- __update_cpu_load(this_rq, 0, pending_updates, 0);
+ __update_cpu_load(this_rq, load, pending_updates, active);
}
raw_spin_unlock(&this_rq->lock);
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 7c7ec45..515edf3 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -694,11 +694,11 @@ out:
return tick;
}
-static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
+static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now, int active)
{
/* Update jiffies first */
tick_do_update_jiffies64(now);
- update_cpu_load_nohz();
+ update_cpu_load_nohz(active);
calc_load_exit_idle();
touch_softlockup_watchdog();
@@ -725,7 +725,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts)
if (can_stop_full_tick())
tick_nohz_stop_sched_tick(ts, ktime_get(), cpu);
else if (ts->tick_stopped)
- tick_nohz_restart_sched_tick(ts, ktime_get());
+ tick_nohz_restart_sched_tick(ts, ktime_get(), 1);
#endif
}
@@ -916,7 +916,7 @@ void tick_nohz_idle_exit(void)
tick_nohz_stop_idle(ts, now);
if (ts->tick_stopped) {
- tick_nohz_restart_sched_tick(ts, now);
+ tick_nohz_restart_sched_tick(ts, now, 0);
tick_nohz_account_idle_ticks(ts);
}
--
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