From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
John Stultz <john.stultz@linaro.org>,
Eric Dumazet <edumazet@google.com>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
linux-pm@vger.kernel.org, Arjan van de Ven <arjan@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Rik van Riel <riel@redhat.com>
Subject: [patch 03/10] timers: Rework idle logic
Date: Mon, 17 Apr 2017 20:32:44 +0200 [thread overview]
Message-ID: <20170417184356.210595106@linutronix.de> (raw)
In-Reply-To: 20170417183241.244217993@linutronix.de
[-- Attachment #1: timers--Rework-idle-logic.patch --]
[-- Type: text/plain, Size: 3085 bytes --]
Storing next event and determining whether the base is idle can be done in
__next_timer_interrupt().
Preparatory patch for new call sites which need this information as well.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/timer.c | 43 ++++++++++++++++++++++++-------------------
1 file changed, 24 insertions(+), 19 deletions(-)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1358,8 +1358,11 @@ static int next_pending_bucket(struct ti
/*
* Search the first expiring timer in the various clock levels. Caller must
* hold base->lock.
+ *
+ * Stores the next expiry time in base. The return value indicates whether
+ * the base is empty or not.
*/
-static unsigned long __next_timer_interrupt(struct timer_base *base)
+static bool __next_timer_interrupt(struct timer_base *base)
{
unsigned long clk, next, adj;
unsigned lvl, offset = 0;
@@ -1416,7 +1419,10 @@ static unsigned long __next_timer_interr
clk >>= LVL_CLK_SHIFT;
clk += adj;
}
- return next;
+ /* Store the next event in the base */
+ base->next_expiry = next;
+ /* Return whether the base is empty or not */
+ return next == base->clk + NEXT_TIMER_MAX_DELTA;
}
/*
@@ -1465,7 +1471,7 @@ u64 get_next_timer_interrupt(unsigned lo
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
u64 expires = KTIME_MAX;
unsigned long nextevt;
- bool is_max_delta;
+ bool is_empty;
/*
* Pretend that there is no timer pending if the cpu is offline.
@@ -1475,9 +1481,8 @@ u64 get_next_timer_interrupt(unsigned lo
return expires;
spin_lock(&base->lock);
- nextevt = __next_timer_interrupt(base);
- is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
- base->next_expiry = nextevt;
+ is_empty = __next_timer_interrupt(base);
+ nextevt = base->next_expiry;
/*
* We have a fresh next event. Check whether we can forward the
* base. We can only do that when @basej is past base->clk
@@ -1490,20 +1495,17 @@ u64 get_next_timer_interrupt(unsigned lo
base->clk = nextevt;
}
- if (time_before_eq(nextevt, basej)) {
- expires = basem;
- base->is_idle = false;
- } else {
- if (!is_max_delta)
- expires = basem + (nextevt - basej) * TICK_NSEC;
- /*
- * If we expect to sleep more than a tick, mark the base idle:
- */
- if ((expires - basem) > TICK_NSEC)
- base->is_idle = true;
- }
+ /* Base is idle if the next event is more than a tick away. */
+ base->is_idle = time_after(nextevt, basej + 1);
spin_unlock(&base->lock);
+ if (!is_empty) {
+ /* If we missed a tick already, force 0 delta */
+ if (time_before_eq(nextevt, basej))
+ nextevt = basej;
+ expires = basem + (nextevt - basej) * TICK_NSEC;
+ }
+
return cmp_next_hrtimer_event(basem, expires);
}
@@ -1534,7 +1536,10 @@ static int collect_expired_timers(struct
* the next expiring timer.
*/
if ((long)(jiffies - base->clk) > 2) {
- unsigned long next = __next_timer_interrupt(base);
+ unsigned long next;
+
+ __next_timer_interrupt(base);
+ next = base->next_expiry;
/*
* If the next timer is ahead of time forward to current
next prev parent reply other threads:[~2017-04-17 18:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-17 18:32 [patch 00/10] timer: Move from a push remote at enqueue to a pull at expiry model Thomas Gleixner
2017-04-17 18:32 ` [patch 01/10] timer: Invoke timer_start_debug() where it makes sense Thomas Gleixner
2017-04-17 18:32 ` [patch 02/10] timerqueue: Document return values of timerqueue_add/del() Thomas Gleixner
2017-04-17 18:32 ` Thomas Gleixner [this message]
2017-04-17 18:32 ` [patch 04/10] timer: Keep the pinned timers separate from the others Thomas Gleixner
2017-04-17 18:32 ` [patch 05/10] timer: Retrieve next expiry of pinned/non-pinned timers seperately Thomas Gleixner
2017-04-17 18:32 ` [patch 06/10] timer: Restructure internal locking Thomas Gleixner
2017-04-17 18:32 ` [patch 07/10] tick/sched: Split out jiffies update helper function Thomas Gleixner
2017-04-17 18:32 ` [patch 08/10] timer: Implement the hierarchical pull model Thomas Gleixner
2017-04-17 18:32 ` [patch 09/10] timer/migration: Add tracepoints Thomas Gleixner
2017-04-17 19:09 ` Steven Rostedt
2017-04-17 18:32 ` [patch 10/10] timer: Always queue timers on the local CPU Thomas Gleixner
2017-04-18 13:57 ` [patch 00/10] timer: Move from a push remote at enqueue to a pull at expiry model Rafael J. Wysocki
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