From nobody Tue Feb 10 17:08:05 2026 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 736E0C77B73 for ; Wed, 24 May 2023 07:08:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239965AbjEXHIM (ORCPT ); Wed, 24 May 2023 03:08:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239900AbjEXHHf (ORCPT ); Wed, 24 May 2023 03:07:35 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1212D9B for ; Wed, 24 May 2023 00:07:05 -0700 (PDT) From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1684912023; 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=toZ3+ufortFTTBI6OBlc3a3bWizxyvQL3TeTeVCWUqU=; b=U34zMuW1T+0NnQXAvVtSY/xZY7B7AQ7PK8D6JhE/lZ1vlJJHSyGCug8oKFSSY6GfcUSSem OM4sDozDQ4U0INnjdI3PqmVxW7nh64lVuYkniLfwzSvxwbrJxXCtCa4ZFWTb2i00I6APFe dpt+deuVti3Iz2xiYd7oJ6Tr8tVnItyPTYwLdWzBvigEbXV52YFOFu0at7N7LNQE1zJ653 ouL0EHo+QPmUrip6shzvzXom8mYh+fTYI2YKXsG2zjZBZgGkurWZ2FxKGoLzzUGJG6zU/b pz5DNTg3yX5Y2iKbF2oBAP685kys/zSFqBsNpFRNwB+PeV8ctvXzgGw9Is2Dig== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1684912023; 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=toZ3+ufortFTTBI6OBlc3a3bWizxyvQL3TeTeVCWUqU=; b=8TaUbW9PT2Pjl6QzwXtZA7s6O4RZP3SC15HsBKLr6IdomKYrFDQbeYwL8DNCNf+UBNnkEZ zZ7dqhWkv502wlAA== 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 , Steven Rostedt , Sebastian Siewior , Giovanni Gherdovich , Lukasz Luba , "Gautham R . Shenoy" , Anna-Maria Behnsen , Frederic Weisbecker Subject: [PATCH v7 14/21] timer: Split out "get next timer interrupt" functionality Date: Wed, 24 May 2023 09:06:22 +0200 Message-Id: <20230524070629.6377-15-anna-maria@linutronix.de> In-Reply-To: <20230524070629.6377-1-anna-maria@linutronix.de> References: <20230524070629.6377-1-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 functionality for getting the next timer interrupt in get_next_timer_interrupt() is split into a separate function fetch_next_timer_interrupt() to be usable by other call sites. 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 --- v6: s/splitted/split v5: Update commit message v4: Fix typo in comment --- 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 e4b50760da3f..4bb6c168d106 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1973,6 +1973,46 @@ 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. @@ -2005,7 +2045,7 @@ 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. @@ -2020,8 +2060,11 @@ 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 @@ -2030,21 +2073,6 @@ 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 @@ -2057,6 +2085,9 @@ 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 @@ -2069,31 +2100,9 @@ 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