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From: Thomas Gleixner <tglx@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>,
	John Stultz <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Valentin Schneider <vschneid@redhat.com>,
	x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Eric Dumazet <edumazet@google.com>
Subject: [patch 43/48] hrtimer: Optimize for_each_active_base()
Date: Tue, 24 Feb 2026 17:38:42 +0100	[thread overview]
Message-ID: <20260224163431.599804894@kernel.org> (raw)
In-Reply-To: 20260224163022.795809588@kernel.org

Give the compiler some help to emit way better code.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
 kernel/time/hrtimer.c |   20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -529,22 +529,10 @@ static inline void debug_activate(struct
 	trace_hrtimer_start(timer, mode, was_armed);
 }
 
-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))))
+#define for_each_active_base(base, cpu_base, active)					\
+	for (unsigned int idx = ffs(active); idx--; idx = ffs((active)))		\
+		for (bool done = false; !done; active &= ~(1U << idx))			\
+			for (base = &cpu_base->clock_base[idx]; !done; done = true)
 
 #if defined(CONFIG_NO_HZ_COMMON)
 /*


  parent reply	other threads:[~2026-02-24 16:38 UTC|newest]

Thread overview: 128+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-24 16:35 [patch 00/48] hrtimer,sched: General optimizations and hrtick enablement Thomas Gleixner
2026-02-24 16:35 ` [patch 01/48] sched/eevdf: Fix HRTICK duration Thomas Gleixner
2026-02-28 15:37   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-03-20 14:59     ` Shrikanth Hegde
2026-03-20 15:38       ` Peter Zijlstra
2026-03-20 15:40         ` Shrikanth Hegde
2026-02-24 16:35 ` [patch 02/48] sched/fair: Simplify hrtick_update() Thomas Gleixner
2026-02-28 15:37   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra (Intel)
2026-02-24 16:35 ` [patch 03/48] sched/fair: Make hrtick resched hard Thomas Gleixner
2026-02-28 15:37   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra (Intel)
2026-02-24 16:35 ` [patch 04/48] sched: Avoid ktime_get() indirection Thomas Gleixner
2026-02-28 15:37   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:35 ` [patch 05/48] hrtimer: Avoid pointless reprogramming in __hrtimer_start_range_ns() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:35 ` [patch 06/48] hrtimer: Provide a static branch based hrtimer_hres_enabled() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:35 ` [patch 07/48] sched: Use hrtimer_highres_enabled() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:35 ` [patch 08/48] sched: Optimize hrtimer handling Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:35 ` [patch 09/48] sched/hrtick: Avoid tiny hrtick rearms Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 10/48] hrtimer: Provide LAZY_REARM mode Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:36 ` [patch 11/48] sched/hrtick: Mark hrtick timer LAZY_REARM Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:36 ` [patch 12/48] tick/sched: Avoid hrtimer_cancel/start() sequence Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 13/48] clockevents: Remove redundant CLOCK_EVT_FEAT_KTIME Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 14/48] timekeeping: Allow inlining clocksource::read() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 15/48] x86: Inline TSC reads in timekeeping Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 16/48] x86/apic: Remove pointless fence in lapic_next_deadline() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 17/48] x86/apic: Avoid the PVOPS indirection for the TSC deadline timer Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 18/48] timekeeping: Provide infrastructure for coupled clockevents Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 19/48] clockevents: Provide support for clocksource coupled comparators Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-03-03 18:44   ` [patch 19/48] " Michael Kelley
2026-03-03 19:14     ` Peter Zijlstra
2026-03-23  4:24     ` Michael Kelley
2026-03-23 21:36       ` Thomas Gleixner
2026-03-24  0:22         ` mhklkml
2026-03-24  3:37           ` Michael Kelley
2026-03-24 17:24             ` Thomas Gleixner
2026-03-24 17:34               ` Peter Zijlstra
2026-02-24 16:36 ` [patch 20/48] x86/apic: Enable TSC coupled programming mode Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-03-03  1:29   ` [patch 20/48] " Nathan Chancellor
2026-03-03 14:37     ` Thomas Gleixner
2026-03-03 14:45       ` Thomas Gleixner
2026-03-03 17:38       ` Nathan Chancellor
2026-03-03 20:21         ` Thomas Gleixner
2026-03-03 21:30           ` Nathan Chancellor
2026-03-04 18:40             ` Thomas Gleixner
2026-03-04 18:49               ` [patch 20/48] clocksource: Update clocksource::freq_khz on registration Thomas Gleixner
2026-03-04 19:10                 ` Borislav Petkov
2026-03-04 22:57                 ` Nathan Chancellor
2026-03-05 16:47                 ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-03-03 21:56         ` [PATCH] Subject: timekeeping: Initialize the coupled clocksource conversion completely Thomas Gleixner
2026-03-03 23:16           ` John Stultz
2026-03-05 16:47           ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 21/48] hrtimer: Add debug object init assertion Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:36 ` [patch 22/48] hrtimer: Reduce trace noise in hrtimer_start() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 23/48] hrtimer: Use guards where appropriate Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 24/48] hrtimer: Cleanup coding style and comments Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 25/48] hrtimer: Evaluate timer expiry only once Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 26/48] hrtimer: Replace the bitfield in hrtimer_cpu_base Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 27/48] hrtimer: Convert state and properties to boolean Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 28/48] hrtimer: Optimize for local timers Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 29/48] hrtimer: Use NOHZ information for locality Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 30/48] hrtimer: Separate remove/enqueue handling for local timers Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 31/48] hrtimer: Add hrtimer_rearm tracepoint Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 32/48] hrtimer: Re-arrange hrtimer_interrupt() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:37 ` [patch 33/48] hrtimer: Rename hrtimer_cpu_base::in_hrtirq to deferred_rearm Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:37 ` [patch 34/48] hrtimer: Prepare stubs for deferred rearming Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:38 ` [patch 35/48] entry: Prepare for deferred hrtimer rearming Thomas Gleixner
2026-02-27 15:57   ` Christian Loehle
2026-02-27 16:25     ` Peter Zijlstra
2026-02-27 16:32       ` Christian Loehle
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:38 ` [patch 36/48] softirq: " Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:38 ` [patch 37/48] sched/core: " Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:38 ` [patch 38/48] hrtimer: Push reprogramming timers into the interrupt return path Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-24 16:38 ` [patch 39/48] hrtimer: Avoid re-evaluation when nothing changed Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` [patch 40/48] hrtimer: Keep track of first expiring timer per clock base Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` [patch 41/48] hrtimer: Rework next event evaluation Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` [patch 42/48] hrtimer: Simplify run_hrtimer_queues() Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` Thomas Gleixner [this message]
2026-02-28 15:36   ` [tip: sched/hrtick] hrtimer: Optimize for_each_active_base() tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` [patch 44/48] rbtree: Provide rbtree with links Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` [patch 45/48] timerqueue: Provide linked timerqueue Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:38 ` [patch 46/48] hrtimer: Use " Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:39 ` [patch 47/48] hrtimer: Try to modify timers in place Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Thomas Gleixner
2026-02-24 16:39 ` [patch 48/48] sched: Default enable HRTICK when deferred rearming is enabled Thomas Gleixner
2026-02-28 15:36   ` [tip: sched/hrtick] " tip-bot2 for Peter Zijlstra
2026-02-25 15:25 ` [patch 00/48] hrtimer,sched: General optimizations and hrtick enablement Peter Zijlstra
2026-02-25 16:02   ` Thomas Gleixner
2026-03-04 15:59 ` Christian Loehle

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