From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C140DC2B9F7 for ; Mon, 24 May 2021 22:18:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9268D6101B for ; Mon, 24 May 2021 22:18:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234001AbhEXWUJ (ORCPT ); Mon, 24 May 2021 18:20:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:60226 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233981AbhEXWUG (ORCPT ); Mon, 24 May 2021 18:20:06 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6A06B613D8; Mon, 24 May 2021 22:18:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621894718; bh=rVROoMYzV0Zl9GKqjghm+Y7uXyhM9mPp8RQdtRYT73Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O86v/DRs6GuxOVZxJ2rAQw1sgtrrxr1qvMTduaL93lgoJQwuzte5sJWpda34zO38x CcXI4LrG9ACHzhLAYPzeSbcppT+G3Y2q9fk0qgOMsAjV5rgIbMZJpfrkNeQQUWqaUb qF0p1iZmjmlCY2heJnj7yeQX+id35ldjo7HsAFDbWBrsBc1WN1ARW2VYZVnv4GECfv AAD5ZfQjEhKTboIjMNydVQFCKyNXSy62JZS5rY1tgmyNQd0osorn+Y1AswCSDLIBAr kBbJljeAgtUEiEuEtai1toPtbwwFVs8e5n6t46IB/28RG1kapeS9FaUPnXqN0kKNmm GkXgvTEi6PgMQ== From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Will Deacon , Frederic Weisbecker , Thomas Gleixner , Marc Zyngier , Lorenzo Colitti , John Stultz , Stephen Boyd , =?UTF-8?q?Mika=20Penttil=C3=A4?= , kernel-team@android.com Subject: [PATCH v2 3/5] tick/broadcast: Prefer per-cpu oneshot wakeup timers to broadcast Date: Mon, 24 May 2021 23:18:16 +0100 Message-Id: <20210524221818.15850-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210524221818.15850-1-will@kernel.org> References: <20210524221818.15850-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some SoCs have two per-cpu timer implementations where the timer with the higher rating stops in deep idle (i.e. suffers from CLOCK_EVT_FEAT_C3STOP) but is otherwise preferable to the timer with the lower rating. In such a design, we rely on a global broadcast timer and IPIs to wake up from deep idle states. To avoid the reliance on a global broadcast timer and also to reduce the overhead associated with the IPI wakeups, extend tick_install_broadcast_device() to manage per-cpu wakeup timers separately from the broadcast device. For now, these timers remain unused. Cc: Frederic Weisbecker Cc: Thomas Gleixner Cc: Marc Zyngier Cc: Lorenzo Colitti Cc: John Stultz Cc: Stephen Boyd Signed-off-by: Will Deacon --- kernel/time/tick-broadcast.c | 59 +++++++++++++++++++++++++++++++++++- kernel/time/tick-common.c | 2 +- kernel/time/tick-internal.h | 4 +-- 3 files changed, 61 insertions(+), 4 deletions(-) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index f3f2f4ba4321..0e9e06d6cc5c 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -33,6 +33,8 @@ static int tick_broadcast_forced; static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock); #ifdef CONFIG_TICK_ONESHOT +static DEFINE_PER_CPU(struct clock_event_device *, tick_oneshot_wakeup_device); + static void tick_broadcast_setup_oneshot(struct clock_event_device *bc); static void tick_broadcast_clear_oneshot(int cpu); static void tick_resume_broadcast_oneshot(struct clock_event_device *bc); @@ -88,13 +90,65 @@ static bool tick_check_broadcast_device(struct clock_event_device *curdev, return !curdev || newdev->rating > curdev->rating; } +#ifdef CONFIG_TICK_ONESHOT +static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu) +{ + return per_cpu(tick_oneshot_wakeup_device, cpu); +} + +static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev, + int cpu) +{ + struct clock_event_device *curdev = tick_get_oneshot_wakeup_device(cpu); + + if (!newdev) + goto set_device; + + if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) || + (newdev->features & CLOCK_EVT_FEAT_C3STOP)) + return false; + + if (!(newdev->features & CLOCK_EVT_FEAT_PERCPU) || + !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) + return false; + + if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) + return false; + + if (curdev && newdev->rating <= curdev->rating) + return false; + + if (!try_module_get(newdev->owner)) + return false; + +set_device: + clockevents_exchange_device(curdev, newdev); + per_cpu(tick_oneshot_wakeup_device, cpu) = newdev; + return true; +} +#else +static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu) +{ + return NULL; +} + +static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev, + int cpu) +{ + return false; +} +#endif + /* * Conditionally install/replace broadcast device */ -void tick_install_broadcast_device(struct clock_event_device *dev) +void tick_install_broadcast_device(struct clock_event_device *dev, int cpu) { struct clock_event_device *cur = tick_broadcast_device.evtdev; + if (tick_set_oneshot_wakeup_device(dev, cpu)) + return; + if (!tick_check_broadcast_device(cur, dev)) return; @@ -996,6 +1050,9 @@ void hotplug_cpu__broadcast_tick_pull(int deadcpu) */ static void tick_broadcast_oneshot_offline(unsigned int cpu) { + if (tick_get_oneshot_wakeup_device(cpu)) + tick_set_oneshot_wakeup_device(NULL, cpu); + /* * Clear the broadcast masks for the dead cpu, but do not stop * the broadcast device! diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index e15bc0ef1912..d663249652ef 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -373,7 +373,7 @@ void tick_check_new_device(struct clock_event_device *newdev) /* * Can the new device be used as a broadcast device ? */ - tick_install_broadcast_device(newdev); + tick_install_broadcast_device(newdev, cpu); } /** diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index 7a981c9e87a4..30c89639e305 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -61,7 +61,7 @@ extern ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt); /* Broadcasting support */ # ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST extern int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu); -extern void tick_install_broadcast_device(struct clock_event_device *dev); +extern void tick_install_broadcast_device(struct clock_event_device *dev, int cpu); extern int tick_is_broadcast_device(struct clock_event_device *dev); extern void tick_suspend_broadcast(void); extern void tick_resume_broadcast(void); @@ -72,7 +72,7 @@ extern int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq); extern struct tick_device *tick_get_broadcast_device(void); extern struct cpumask *tick_get_broadcast_mask(void); # else /* !CONFIG_GENERIC_CLOCKEVENTS_BROADCAST: */ -static inline void tick_install_broadcast_device(struct clock_event_device *dev) { } +static inline void tick_install_broadcast_device(struct clock_event_device *dev, int cpu) { } static inline int tick_is_broadcast_device(struct clock_event_device *dev) { return 0; } static inline int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) { return 0; } static inline void tick_do_periodic_broadcast(struct clock_event_device *d) { } -- 2.31.1.818.g46aad6cb9e-goog