From patchwork Tue Oct 25 13:58:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anna-Maria Behnsen X-Patchwork-Id: 13019283 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 6D6F9C38A2D for ; Tue, 25 Oct 2022 13:59:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232107AbiJYN7k (ORCPT ); Tue, 25 Oct 2022 09:59:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231938AbiJYN7d (ORCPT ); Tue, 25 Oct 2022 09:59:33 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B27C2DC4; Tue, 25 Oct 2022 06:59:27 -0700 (PDT) From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1666706365; 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=Yz5QT49atKnBQG/qBqEE3tDeAp0qP/kdCDP7jVvSCFM=; b=fSks/ca8LpAozeH+YWraVKFk64y/NlxHDqFuNY2NEwhyCgxX6Sp7sJ4Jof1/h7adP8UqqF R83ncl9gPTc5HGmWpLB+MoXBxVahnqKwh9FedrlefYzEW+jQ5ohH3S1T1vHVMaQV8OZMG4 T0a66LDsOPtjXVwlfSiRrW4s1DFFUN0M/MqrJd+ePLz4zapGGNjfXOngA2/5JJqdztu5QX xAhHDd4vpxn30DYdk8TH2e1vAMGPzn9TV9JDroz5CnDMqXP7sLTJLyUHXcKMZS8UfnX/7C 7ikYKpeq+l2EMzys6Sxct7606MvE7pAAWwR8HSghV4liBQhrtLr5zN8DB+swFQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1666706365; 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=Yz5QT49atKnBQG/qBqEE3tDeAp0qP/kdCDP7jVvSCFM=; b=jVY37Lfuu2bepa56hR/qvENwl19HeRKglymqDFH9aH7Xp5wCCz0O2obI5mQe2YTnl9ECyZ KzNtHLjCPEX1SWDg== To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , John Stultz , Eric Dumazet , Thomas Gleixner , "Rafael J. Wysocki" , linux-pm@vger.kernel.org, Arjan van de Ven , "Paul E. McKenney" , Frederic Weisbecker , Rik van Riel , Anna-Maria Behnsen Subject: [PATCH v3 09/17] timer: Split out "get next timer interrupt" functionality Date: Tue, 25 Oct 2022 15:58:42 +0200 Message-Id: <20221025135850.51044-10-anna-maria@linutronix.de> In-Reply-To: <20221025135850.51044-1-anna-maria@linutronix.de> References: <20221025135850.51044-1-anna-maria@linutronix.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org forward_and_idle_timer_bases() includes the functionality for getting the next timer interrupt. To reuse it, it is splitted into an separate function "get_next_timer_interrupt()". 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 --- kernel/time/timer.c | 93 +++++++++++++++++++++++++-------------------- 1 file changed, 51 insertions(+), 42 deletions(-) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 1990eb1b2cc9..167ae89f0f46 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1704,6 +1704,46 @@ static unsigned long next_timer_interrupt(struct timer_base *base) return base->next_expiry; } +static unsigned long get_next_timer_interrupt(struct timer_base *base_local, + 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 = next_timer_interrupt(base_local); + nextevt_global = 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 next_evtlocal 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 = time_before_eq(nextevt_local, nextevt_global); + else + local_first = 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 = basem + (u64)(nextevt_global - basej) * TICK_NSEC; + + if (base_local->timers_pending) + tevt->local = basem + (u64)(nextevt_local - basej) * TICK_NSEC; + + return local_first ? nextevt_local : nextevt_global; +} + /** * forward_and_idle_timer_bases * @basej: base time jiffies @@ -1723,7 +1763,7 @@ void forward_and_idle_timer_bases(unsigned long basej, u64 basem, { unsigned long nextevt, nextevt_local, nextevt_global; struct timer_base *base_local, *base_global; - bool local_first, is_idle; + bool is_idle; /* Preset local / global events */ tevt->local = tevt->global = KTIME_MAX; @@ -1741,8 +1781,11 @@ void forward_and_idle_timer_bases(unsigned long basej, u64 basem, raw_spin_lock(&base_local->lock); raw_spin_lock_nested(&base_global->lock, SINGLE_DEPTH_NESTING); - nextevt_local = next_timer_interrupt(base_local); - nextevt_global = next_timer_interrupt(base_global); + nextevt = get_next_timer_interrupt(base_local, base_global, + basej, basem, tevt); + + nextevt_local = base_local->next_expiry; + nextevt_global = base_global->next_expiry; /* * We have a fresh next event. Check whether we can forward the @@ -1763,21 +1806,6 @@ void forward_and_idle_timer_bases(unsigned long basej, u64 basem, base_global->clk = nextevt_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 = time_before_eq(nextevt_local, nextevt_global); - else - local_first = base_local->timers_pending; - - nextevt = 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 @@ -1790,43 +1818,24 @@ void forward_and_idle_timer_bases(unsigned long basej, u64 basem, /* We need to mark both bases in sync */ base_local->is_idle = base_global->is_idle = is_idle; + 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 * sleep. Use the earlier event of both and store it in the local * expiry value. The next global event is irrelevant in this case - * and can be left as KTIME_MAX. CPU will wakeup on time. + * and can be reset as KTIME_MAX. CPU will wakeup on time. */ if (!is_idle) { /* If we missed a tick already, force 0 delta */ if (time_before_eq(nextevt, basej)) nextevt = basej; tevt->local = basem + (u64)(nextevt - basej) * TICK_NSEC; - goto unlock; + tevt->global = KTIME_MAX; } - /* - * 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 = 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 = basem + (u64)(nextevt_global - basej) * TICK_NSEC; - -unlock: - raw_spin_unlock(&base_global->lock); - raw_spin_unlock(&base_local->lock); - cmp_next_hrtimer_event(basem, tevt); }