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Date: Mon, 19 Jun 2017 04:12:00 +0200
From: Frederic Weisbecker <fweisbec@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Rik van Riel <riel@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 1/3] sched/loadavg: Generalize idle naming to nohz
The loadavg naming code still assumes that nohz == idle whereas its code
is actually handling well both nohz idle and nohz full.
So lets fix the naming according to what the code actually does.
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
---
Documentation/trace/ftrace.txt | 2 +-
include/linux/sched/nohz.h | 8 +++----
kernel/sched/loadavg.c | 51 +++++++++++++++++++++---------------------
kernel/time/tick-sched.c | 4 ++--
4 files changed, 33 insertions(+), 32 deletions(-)
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 94a987b..fff8ff6 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -1609,7 +1609,7 @@ Doing the same with chrt -r 5 and function-trace set.
<idle>-0 3dN.2 14us : sched_avg_update <-__cpu_load_update
<idle>-0 3dN.2 14us : _raw_spin_unlock <-cpu_load_update_nohz
<idle>-0 3dN.2 14us : sub_preempt_count <-_raw_spin_unlock
- <idle>-0 3dN.1 15us : calc_load_exit_idle <-tick_nohz_idle_exit
+ <idle>-0 3dN.1 15us : calc_load_nohz_stop <-tick_nohz_idle_exit
<idle>-0 3dN.1 15us : touch_softlockup_watchdog <-tick_nohz_idle_exit
<idle>-0 3dN.1 15us : hrtimer_cancel <-tick_nohz_idle_exit
<idle>-0 3dN.1 15us : hrtimer_try_to_cancel <-hrtimer_cancel
diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h
index 4995b71..7d3f75d 100644
--- a/include/linux/sched/nohz.h
+++ b/include/linux/sched/nohz.h
@@ -23,11 +23,11 @@ static inline void set_cpu_sd_state_idle(void) { }
#endif
#ifdef CONFIG_NO_HZ_COMMON
-void calc_load_enter_idle(void);
-void calc_load_exit_idle(void);
+void calc_load_nohz_start(void);
+void calc_load_nohz_stop(void);
#else
-static inline void calc_load_enter_idle(void) { }
-static inline void calc_load_exit_idle(void) { }
+static inline void calc_load_nohz_start(void) { }
+static inline void calc_load_nohz_stop(void) { }
#endif /* CONFIG_NO_HZ_COMMON */
#if defined(CONFIG_NO_HZ_COMMON) && defined(CONFIG_SMP)
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index f15fb2b..f14716a 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -117,7 +117,7 @@ calc_load(unsigned long load, unsigned long exp, unsigned long active)
* load-average relies on per-cpu sampling from the tick, it is affected by
* NO_HZ.
*
- * The basic idea is to fold the nr_active delta into a global idle-delta upon
+ * The basic idea is to fold the nr_active delta into a global NO_HZ-delta upon
* entering NO_HZ state such that we can include this as an 'extra' cpu delta
* when we read the global state.
*
@@ -126,7 +126,7 @@ calc_load(unsigned long load, unsigned long exp, unsigned long active)
* - When we go NO_HZ idle during the window, we can negate our sample
* contribution, causing under-accounting.
*
- * We avoid this by keeping two idle-delta counters and flipping them
+ * We avoid this by keeping two NO_HZ-delta counters and flipping them
* when the window starts, thus separating old and new NO_HZ load.
*
* The only trick is the slight shift in index flip for read vs write.
@@ -137,22 +137,22 @@ calc_load(unsigned long load, unsigned long exp, unsigned long active)
* r:0 0 1 1 0 0 1 1 0
* w:0 1 1 0 0 1 1 0 0
*
- * This ensures we'll fold the old idle contribution in this window while
+ * This ensures we'll fold the old NO_HZ contribution in this window while
* accumlating the new one.
*
- * - When we wake up from NO_HZ idle during the window, we push up our
+ * - When we wake up from NO_HZ during the window, we push up our
* contribution, since we effectively move our sample point to a known
* busy state.
*
* This is solved by pushing the window forward, and thus skipping the
- * sample, for this cpu (effectively using the idle-delta for this cpu which
+ * sample, for this cpu (effectively using the NO_HZ-delta for this cpu which
* was in effect at the time the window opened). This also solves the issue
- * of having to deal with a cpu having been in NOHZ idle for multiple
- * LOAD_FREQ intervals.
+ * of having to deal with a cpu having been in NO_HZ for multiple LOAD_FREQ
+ * intervals.
*
* When making the ILB scale, we should try to pull this in as well.
*/
-static atomic_long_t calc_load_idle[2];
+static atomic_long_t calc_load_nohz[2];
static int calc_load_idx;
static inline int calc_load_write_idx(void)
@@ -167,7 +167,7 @@ static inline int calc_load_write_idx(void)
/*
* If the folding window started, make sure we start writing in the
- * next idle-delta.
+ * next NO_HZ-delta.
*/
if (!time_before(jiffies, READ_ONCE(calc_load_update)))
idx++;
@@ -180,24 +180,24 @@ static inline int calc_load_read_idx(void)
return calc_load_idx & 1;
}
-void calc_load_enter_idle(void)
+void calc_load_nohz_start(void)
{
struct rq *this_rq = this_rq();
long delta;
/*
- * We're going into NOHZ mode, if there's any pending delta, fold it
- * into the pending idle delta.
+ * We're going into NO_HZ mode, if there's any pending delta, fold it
+ * into the pending NO_HZ delta.
*/
delta = calc_load_fold_active(this_rq, 0);
if (delta) {
int idx = calc_load_write_idx();
- atomic_long_add(delta, &calc_load_idle[idx]);
+ atomic_long_add(delta, &calc_load_nohz[idx]);
}
}
-void calc_load_exit_idle(void)
+void calc_load_nohz_stop(void)
{
struct rq *this_rq = this_rq();
@@ -217,13 +217,13 @@ void calc_load_exit_idle(void)
this_rq->calc_load_update += LOAD_FREQ;
}
-static long calc_load_fold_idle(void)
+static long calc_load_nohz_fold(void)
{
int idx = calc_load_read_idx();
long delta = 0;
- if (atomic_long_read(&calc_load_idle[idx]))
- delta = atomic_long_xchg(&calc_load_idle[idx], 0);
+ if (atomic_long_read(&calc_load_nohz[idx]))
+ delta = atomic_long_xchg(&calc_load_nohz[idx], 0);
return delta;
}
@@ -299,9 +299,9 @@ calc_load_n(unsigned long load, unsigned long exp,
/*
* NO_HZ can leave us missing all per-cpu ticks calling
- * calc_load_account_active(), but since an idle CPU folds its delta into
- * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
- * in the pending idle delta if our idle period crossed a load cycle boundary.
+ * calc_load_fold_active(), but since a NO_HZ CPU folds its delta into
+ * calc_load_nohz per calc_load_nohz_start(), all we need to do is fold
+ * in the pending NO_HZ delta if our NO_HZ period crossed a load cycle boundary.
*
* Once we've updated the global active value, we need to apply the exponential
* weights adjusted to the number of cycles missed.
@@ -330,7 +330,7 @@ static void calc_global_nohz(void)
}
/*
- * Flip the idle index...
+ * Flip the NO_HZ index...
*
* Make sure we first write the new time then flip the index, so that
* calc_load_write_idx() will see the new time when it reads the new
@@ -341,7 +341,7 @@ static void calc_global_nohz(void)
}
#else /* !CONFIG_NO_HZ_COMMON */
-static inline long calc_load_fold_idle(void) { return 0; }
+static inline long calc_load_nohz_fold(void) { return 0; }
static inline void calc_global_nohz(void) { }
#endif /* CONFIG_NO_HZ_COMMON */
@@ -362,9 +362,9 @@ void calc_global_load(unsigned long ticks)
return;
/*
- * Fold the 'old' idle-delta to include all NO_HZ cpus.
+ * Fold the 'old' NO_HZ-delta to include all NO_HZ cpus.
*/
- delta = calc_load_fold_idle();
+ delta = calc_load_nohz_fold();
if (delta)
atomic_long_add(delta, &calc_load_tasks);
@@ -378,7 +378,8 @@ void calc_global_load(unsigned long ticks)
WRITE_ONCE(calc_load_update, sample_window + LOAD_FREQ);
/*
- * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk.
+ * In case we went to NO_HZ for multiple LOAD_FREQ intervals
+ * catch up in bulk.
*/
calc_global_nohz();
}
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 2046009..1c9a508 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -786,7 +786,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
*/
if (!ts->tick_stopped) {
nohz_balance_enter_idle(cpu);
- calc_load_enter_idle();
+ calc_load_nohz_start();
cpu_load_update_nohz_start();
ts->last_tick = hrtimer_get_expires(&ts->sched_timer);
@@ -833,7 +833,7 @@ static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now)
*/
timer_clear_idle();
- calc_load_exit_idle();
+ calc_load_nohz_stop();
touch_softlockup_watchdog_sched();
/*
* Cancel the scheduled timer and restore the tick
--
2.7.4
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