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From: tip-bot for Anna-Maria Gleixner <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: hch@lst.de, tglx@linutronix.de, anna-maria@linutronix.de,
	peterz@infradead.org, torvalds@linux-foundation.org,
	mingo@kernel.org, john.stultz@linaro.org,
	linux-kernel@vger.kernel.org, hpa@zytor.com
Subject: [tip:timers/core] hrtimer: Switch 'for' loop to _ffs() evaluation
Date: Mon, 15 Jan 2018 19:44:17 -0800	[thread overview]
Message-ID: <tip-c272ca58c3ec5631f4ab507489d9477f74efe645@git.kernel.org> (raw)
In-Reply-To: <20171221104205.7269-11-anna-maria@linutronix.de>

Commit-ID:  c272ca58c3ec5631f4ab507489d9477f74efe645
Gitweb:     https://git.kernel.org/tip/c272ca58c3ec5631f4ab507489d9477f74efe645
Author:     Anna-Maria Gleixner <anna-maria@linutronix.de>
AuthorDate: Thu, 21 Dec 2017 11:41:39 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 16 Jan 2018 02:35:46 +0100

hrtimer: Switch 'for' loop to _ffs() evaluation

Looping over all clock bases to find active bits is suboptimal if not all
bases are active.

Avoid this by converting it to a __ffs() evaluation. The functionallity is
outsourced into its own function and is called via a macro as suggested by
Peter Zijlstra.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-11-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/time/hrtimer.c | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index f4f4658..cfcf8de 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -448,6 +448,23 @@ static inline void debug_deactivate(struct hrtimer *timer)
 	trace_hrtimer_cancel(timer);
 }
 
+static struct hrtimer_clock_base *
+__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
+{
+	unsigned int idx;
+
+	if (!*active)
+		return NULL;
+
+	idx = __ffs(*active);
+	*active &= ~(1U << idx);
+
+	return &cpu_base->clock_base[idx];
+}
+
+#define for_each_active_base(base, cpu_base, active)	\
+	while ((base = __next_base((cpu_base), &(active))))
+
 #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
 static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
 					     struct hrtimer *timer)
@@ -459,18 +476,15 @@ static inline void hrtimer_update_next_timer(struct hrtimer_cpu_base *cpu_base,
 
 static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
 {
-	struct hrtimer_clock_base *base = cpu_base->clock_base;
+	struct hrtimer_clock_base *base;
 	unsigned int active = cpu_base->active_bases;
 	ktime_t expires, expires_next = KTIME_MAX;
 
 	hrtimer_update_next_timer(cpu_base, NULL);
-	for (; active; base++, active >>= 1) {
+	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *next;
 		struct hrtimer *timer;
 
-		if (!(active & 0x01))
-			continue;
-
 		next = timerqueue_getnext(&base->active);
 		timer = container_of(next, struct hrtimer, node);
 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
@@ -1241,16 +1255,13 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
 
 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now)
 {
-	struct hrtimer_clock_base *base = cpu_base->clock_base;
+	struct hrtimer_clock_base *base;
 	unsigned int active = cpu_base->active_bases;
 
-	for (; active; base++, active >>= 1) {
+	for_each_active_base(base, cpu_base, active) {
 		struct timerqueue_node *node;
 		ktime_t basenow;
 
-		if (!(active & 0x01))
-			continue;
-
 		basenow = ktime_add(now, base->offset);
 
 		while ((node = timerqueue_getnext(&base->active))) {

  reply	other threads:[~2018-01-16  3:47 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-21 10:41 [PATCH v4 00/36] hrtimer: Provide softirq context hrtimers Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 01/36] timers: Use static keys for migrate_enable/nohz_active Anna-Maria Gleixner
2017-12-22 15:45   ` [PATCH v5 " Sebastian Andrzej Siewior
2018-01-14 22:13     ` Thomas Gleixner
2018-01-14 22:30       ` [PATCH v6 " Thomas Gleixner
2018-01-11  4:25   ` [PATCH v4 " Frederic Weisbecker
2018-01-16  3:40   ` [tip:timers/core] hrtimer: Optimize the hrtimer code by using static keys for migration_enable/nohz_active tip-bot for Thomas Gleixner
2017-12-21 10:41 ` [PATCH v4 02/36] hrtimer: Correct blantanly wrong comment Anna-Maria Gleixner
2018-01-11 18:28   ` Frederic Weisbecker
2018-01-16  1:02   ` Ingo Molnar
2018-01-16  3:40   ` [tip:timers/core] hrtimer: Correct blatantly incorrect comment tip-bot for Thomas Gleixner
2017-12-21 10:41 ` [PATCH v4 03/36] hrtimer: Fix kerneldoc for struct hrtimer_cpu_base Anna-Maria Gleixner
2018-01-16  3:41   ` [tip:timers/core] hrtimer: Fix kerneldoc syntax for 'struct hrtimer_cpu_base' tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 04/36] hrtimer: Cleanup clock argument in schedule_hrtimeout_range_clock() Anna-Maria Gleixner
2018-01-16  3:41   ` [tip:timers/core] hrtimer: Clean up the 'int clock' parameter of schedule_hrtimeout_range_clock() tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 05/36] hrtimer: Fix hrtimer function description Anna-Maria Gleixner
2018-01-16  3:42   ` [tip:timers/core] hrtimer: Fix hrtimer_start[_range_ns]() function descriptions tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 06/36] hrtimer: Ensure POSIX compliance (relative CLOCK_REALTIME hrtimers) Anna-Maria Gleixner
2018-01-16  3:42   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 07/36] hrtimer: Cleanup hrtimer_mode enum Anna-Maria Gleixner
2018-01-16  3:43   ` [tip:timers/core] hrtimer: Clean up 'enum hrtimer_mode' tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 08/36] tracing/hrtimer: Take all clock bases and modes into account Anna-Maria Gleixner
2018-01-16  3:43   ` [tip:timers/core] tracing/hrtimer: Fix tracing bugs by taking " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 09/36] tracing/hrtimer: Print hrtimer mode in hrtimer_start tracepoint Anna-Maria Gleixner
2018-01-16  3:43   ` [tip:timers/core] tracing/hrtimer: Print the hrtimer mode in the 'hrtimer_start' tracepoint tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 10/36] hrtimer: Switch for loop to _ffs() evaluation Anna-Maria Gleixner
2018-01-16  3:44   ` tip-bot for Anna-Maria Gleixner [this message]
2017-12-21 10:41 ` [PATCH v4 11/36] hrtimer: Store running timer in hrtimer_clock_base Anna-Maria Gleixner
2018-01-16  3:44   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 12/36] hrtimer: Make room in struct hrtimer_cpu_base Anna-Maria Gleixner
2018-01-16  3:45   ` [tip:timers/core] hrtimer: Make room in 'struct hrtimer_cpu_base' tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 13/36] hrtimer: Reduce conditional code (hres_active) Anna-Maria Gleixner
2018-01-16  3:45   ` [tip:timers/core] hrtimer: Make the hrtimer_cpu_base::hres_active field unconditional, to simplify the code tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 14/36] hrtimer: Use accesor functions instead of direct access Anna-Maria Gleixner
2018-01-16  3:46   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 15/36] hrtimer: Make the remote enqueue check unconditional Anna-Maria Gleixner
2018-01-16  3:46   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 16/36] hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional Anna-Maria Gleixner
2018-01-16  3:46   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 17/36] hrtimer: Make hrtimer_reprogramm() unconditional Anna-Maria Gleixner
2018-01-16  3:47   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 18/36] hrtimer: Make hrtimer_force_reprogramm() unconditionally available Anna-Maria Gleixner
2018-01-16  3:47   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 19/36] hrtimer: Unify handling of hrtimer remove Anna-Maria Gleixner
2018-01-16  3:48   ` [tip:timers/core] hrtimer: Unify hrtimer removal handling tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 20/36] hrtimer: Unify handling of remote enqueue Anna-Maria Gleixner
2018-01-16  3:48   ` [tip:timers/core] hrtimer: Unify remote enqueue handling tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 21/36] hrtimer: Make remote enqueue decision less restrictive Anna-Maria Gleixner
2018-01-16  3:49   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 22/36] hrtimer: Remove base argument from hrtimer_reprogram() Anna-Maria Gleixner
2018-01-16  3:49   ` [tip:timers/core] hrtimer: Remove the 'base' parameter " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 23/36] hrtimer: Split hrtimer_start_range_ns() Anna-Maria Gleixner
2018-01-16  3:49   ` [tip:timers/core] hrtimer: Factor out __hrtimer_start_range_ns() tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 24/36] hrtimer: Split __hrtimer_get_next_event() Anna-Maria Gleixner
2018-01-16  3:50   ` [tip:timers/core] hrtimer: Factor out __hrtimer_next_event_base() tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 25/36] hrtimer: Use irqsave/irqrestore around __run_hrtimer() Anna-Maria Gleixner
2018-01-16  3:50   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 26/36] hrtimer: Add clock bases and hrtimer mode for soft irq context Anna-Maria Gleixner
2018-01-16  3:51   ` [tip:timers/core] hrtimer: Add clock bases and hrtimer mode for softirq context tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 27/36] hrtimer: Prepare handling of hard and softirq based hrtimers Anna-Maria Gleixner
2018-01-16  3:51   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 28/36] hrtimer: Implement support for " Anna-Maria Gleixner
2018-01-16 10:22   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 29/36] hrtimer: Implement SOFT/HARD clock base selection Anna-Maria Gleixner
2018-01-16 10:22   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2017-12-21 10:41 ` [PATCH v4 30/36] can/bcm: Replace hrtimer_tasklet with softirq based hrtimer Anna-Maria Gleixner
2017-12-21 10:42 ` [PATCH v4 31/36] mac80211_hwsim: Replace hrtimer tasklet with softirq hrtimer Anna-Maria Gleixner
2018-01-04 15:12   ` Johannes Berg
2018-01-04 15:18     ` Thomas Gleixner
2017-12-21 10:42 ` [PATCH v4 32/36] xfrm: " Anna-Maria Gleixner
2017-12-21 10:42 ` [PATCH v4 33/36] softirq: Remove tasklet_hrtimer Anna-Maria Gleixner
2017-12-21 10:42 ` [PATCH v4 34/36] ALSA/dummy: Replace tasklet with softirq hrtimer Anna-Maria Gleixner
2017-12-21 10:42   ` Anna-Maria Gleixner
2018-01-16 10:23   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2017-12-21 10:42 ` [PATCH v4 35/36] usb/gadget/NCM: " Anna-Maria Gleixner
2017-12-21 10:42   ` [v4,35/36] " Anna-Maria Gleixner
2018-01-16 10:23   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2017-12-21 10:42 ` [PATCH v4 36/36] net/mvpp2: " Anna-Maria Gleixner
2018-01-16  1:39 ` [PATCH v4 00/36] hrtimer: Provide softirq context hrtimers Ingo Molnar
2018-01-16  2:03   ` Ingo Molnar

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