From nobody Wed Sep 10 02:03:21 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E7B8C6FA9D for ; Wed, 1 Mar 2023 14:19:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230168AbjCAOTL (ORCPT ); Wed, 1 Mar 2023 09:19:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230061AbjCAOSK (ORCPT ); Wed, 1 Mar 2023 09:18:10 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D34372ED74 for ; Wed, 1 Mar 2023 06:18:08 -0800 (PST) From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1677680287; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K7TGxAEPdX981ks1AGMS1UlpllpfQeWHwCRWcpqbDH4=; b=Vwz1hm8GpxV4mAbvHzX+bYSBwH3s2J7efJtHwSAtxsxCx0Q1JijqU0uSjKR0Npp9KgGOnE ltWygBSCWq3bcMghCM1DDOzdogwikwr2nl3VkXkKrpCm//3FSkVbuqc5KrOuFZ7t0c4UAk wi2igyAEA2/RiuOTYDwOMR2Qma26oGZbFTd9/5Ias2RaWEVT2ijixzEVXFHcIWYJnC3QUl MXowSvk9tfKtrR4YqXZCzWGWh8p5b69u5a3CqjtEhHpUlK9lAhj8iFO7OoDIANgJkVKi/8 CXQbKWRtloioiI8INCj/9U4VDpFESHnKiAa6v2jQs1GTECNaweziFEle+35dsg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1677680287; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=K7TGxAEPdX981ks1AGMS1UlpllpfQeWHwCRWcpqbDH4=; b=iGABhEL79yPDYZWtKAVio4p4u/KtoHqBn2Gnhm87dX337g0/y1KyE5HGvYzKXcCw9YSOum cgtnXN+2ADyoIbAw== To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , John Stultz , Thomas Gleixner , Eric Dumazet , "Rafael J . Wysocki" , Arjan van de Ven , "Paul E . McKenney" , Frederic Weisbecker , Rik van Riel , Anna-Maria Behnsen Subject: [PATCH v5 11/18] timer: Split out "get next timer interrupt" functionality Date: Wed, 1 Mar 2023 15:17:37 +0100 Message-Id: <20230301141744.16063-12-anna-maria@linutronix.de> In-Reply-To: <20230301141744.16063-1-anna-maria@linutronix.de> References: <20230301141744.16063-1-anna-maria@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The functionallity for getting the next timer interrupt in get_next_timer_interrupt() is splitted into a separate function fetch_next_timer_interrupt() to be usable by other callsides. This is preparatory work for the conversion of the NOHZ timer placement to a pull at expiry time model. No functional change. Signed-off-by: Anna-Maria Behnsen Reviewed-by: Frederic Weisbecker --- v5: Update commit message --- kernel/time/timer.c | 91 +++++++++++++++++++++++++-------------------- 1 file changed, 50 insertions(+), 41 deletions(-) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index ff41d978cb22..dfc744545159 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1944,6 +1944,46 @@ static unsigned long next_timer_interrupt(struct tim= er_base *base) return base->next_expiry; } =20 +static unsigned long fetch_next_timer_interrupt(struct timer_base *base_lo= cal, + struct timer_base *base_global, + unsigned long basej, u64 basem, + struct timer_events *tevt) +{ + unsigned long nextevt_local, nextevt_global; + bool local_first; + + nextevt_local =3D next_timer_interrupt(base_local); + nextevt_global =3D next_timer_interrupt(base_global); + + /* + * Check whether the local event is expiring before or at the same + * time as the global event. + * + * Note, that nextevt_global and nextevt_local might be based on + * different base->clk values. So it's not guaranteed that + * comparing with empty bases results in a correct local_first. + */ + if (base_local->timers_pending && base_global->timers_pending) + local_first =3D time_before_eq(nextevt_local, nextevt_global); + else + local_first =3D base_local->timers_pending; + + /* + * Update tevt->* values: + * + * If the local queue expires first, then the global event can + * be ignored. If the global queue is empty, nothing to do + * either. + */ + if (!local_first && base_global->timers_pending) + tevt->global =3D basem + (u64)(nextevt_global - basej) * TICK_NSEC; + + if (base_local->timers_pending) + tevt->local =3D basem + (u64)(nextevt_local - basej) * TICK_NSEC; + + return local_first ? nextevt_local : nextevt_global; +} + /* * Forward base clock is done only when @basej is past base->clk, otherwise * base-clk might be rewind. @@ -1976,7 +2016,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64= basem) struct timer_events tevt =3D { .local =3D KTIME_MAX, .global =3D KTIME_MA= X }; unsigned long nextevt, nextevt_local, nextevt_global; struct timer_base *base_local, *base_global; - bool local_first, is_idle; + bool is_idle; =20 /* * Pretend that there is no timer pending if the cpu is offline. @@ -1991,8 +2031,11 @@ u64 get_next_timer_interrupt(unsigned long basej, u6= 4 basem) raw_spin_lock(&base_local->lock); raw_spin_lock_nested(&base_global->lock, SINGLE_DEPTH_NESTING); =20 - nextevt_local =3D next_timer_interrupt(base_local); - nextevt_global =3D next_timer_interrupt(base_global); + nextevt =3D fetch_next_timer_interrupt(base_local, base_global, + basej, basem, &tevt); + + nextevt_local =3D base_local->next_expiry; + nextevt_global =3D base_global->next_expiry; =20 /* * We have a fresh next event. Check whether we can forward the @@ -2001,21 +2044,6 @@ u64 get_next_timer_interrupt(unsigned long basej, u6= 4 basem) forward_base_clk(base_local, nextevt_local, basej); forward_base_clk(base_global, nextevt_global, basej); =20 - /* - * Check whether the local event is expiring before or at the same - * time as the global event. - * - * Note, that nextevt_global and nextevt_local might be based on - * different base->clk values. So it's not guaranteed that - * comparing with empty bases results in a correct local_first. - */ - if (base_local->timers_pending && base_global->timers_pending) - local_first =3D time_before_eq(nextevt_local, nextevt_global); - else - local_first =3D base_local->timers_pending; - - nextevt =3D local_first ? nextevt_local : nextevt_global; - /* * Bases are idle if the next event is more than a tick away. Also * the tick is stopped so any added timer must forward the base clk @@ -2028,6 +2056,9 @@ u64 get_next_timer_interrupt(unsigned long basej, u64= basem) /* We need to mark both bases in sync */ base_local->is_idle =3D base_global->is_idle =3D is_idle; =20 + raw_spin_unlock(&base_global->lock); + raw_spin_unlock(&base_local->lock); + /* * If the bases are not marked idle, i.e one of the events is at * max. one tick away, then the CPU can't go into a NOHZ idle @@ -2040,31 +2071,9 @@ u64 get_next_timer_interrupt(unsigned long basej, u6= 4 basem) if (time_before(nextevt, basej)) nextevt =3D basej; tevt.local =3D basem + (u64)(nextevt - basej) * TICK_NSEC; - goto unlock; + tevt.global =3D KTIME_MAX; } =20 - /* - * If the bases are marked idle, i.e. the next event on both the - * local and the global queue are farther away than a tick, - * evaluate both bases. No need to check whether one of the bases - * has an already expired timer as this is caught by the !is_idle - * condition above. - */ - if (base_local->timers_pending) - tevt.local =3D basem + (u64)(nextevt_local - basej) * TICK_NSEC; - - /* - * If the local queue expires first, then the global event can be - * ignored. The CPU wakes up before that. If the global queue is - * empty, nothing to do either. - */ - if (!local_first && base_global->timers_pending) - tevt.global =3D basem + (u64)(nextevt_global - basej) * TICK_NSEC; - -unlock: - raw_spin_unlock(&base_global->lock); - raw_spin_unlock(&base_local->lock); - tevt.local =3D min_t(u64, tevt.local, tevt.global); =20 return cmp_next_hrtimer_event(basem, tevt.local); --=20 2.30.2