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Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1ljnhh-00GaEU-C2 for linux-arm-kernel@lists.infradead.org; Thu, 20 May 2021 18:47:30 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5429F611AE; Thu, 20 May 2021 18:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621536449; bh=5M3iD+6AYgGmTxRsjr17d+oS5yIoXNVuSfoJm4ysB5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=t/m4YnaEcrFXutACKlfnFds4FMzkNxpALBpbe73uYs03ELhEuXwJGYgJPUTV6Ds8S qc/lhFKc/G6CoecfM65h/UA7ZukCb3NyZ9GgZcBEuRPy9zsw5qODbQ+cdWmCoFZ7+4 z1yz5UeAZ2OwO+FPDXLvXP1H0KWDgxGIIWysce9TArYQdVC754iOvuRkdoor3TDcgb Jw+SBbKiLUdb0NcRfGUQFb4vd9RkwXZx4UPScBWEAVMGZfddixqqwC5eKklF9lKyxs qEQ2y2fzr3Z38Wa7nC1QAj+ATfEHFiC3tq0a4gj6gsSZQJL8YSigjK3DCRUukPM1/z uv1hGx0/aYg1g== 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 , kernel-team@android.com Subject: [PATCH 3/5] tick/broadcast: Prefer per-cpu oneshot wakeup timers to broadcast Date: Thu, 20 May 2021 19:47:03 +0100 Message-Id: <20210520184705.10845-4-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210520184705.10845-1-will@kernel.org> References: <20210520184705.10845-1-will@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210520_114729_469831_91B4CB49 X-CRM114-Status: GOOD ( 18.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 | 57 +++++++++++++++++++++++++++++++++++- kernel/time/tick-common.c | 2 +- kernel/time/tick-internal.h | 4 +-- 3 files changed, 59 insertions(+), 4 deletions(-) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index f3f2f4ba4321..8bd8cd69c8c9 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 +90,59 @@ 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; + + if (!newdev) + goto set_device; + + if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) || + (newdev->features & CLOCK_EVT_FEAT_C3STOP) || + !(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) + return false; + + if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu))) + return false; + + curdev = tick_get_oneshot_wakeup_device(cpu); + if (curdev && newdev->rating <= curdev->rating) + return false; + +set_device: + 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 +1044,13 @@ void hotplug_cpu__broadcast_tick_pull(int deadcpu) */ static void tick_broadcast_oneshot_offline(unsigned int cpu) { + struct clock_event_device *dev = tick_get_oneshot_wakeup_device(cpu); + + if (dev) { + clockevents_switch_state(dev, CLOCK_EVT_STATE_DETACHED); + 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) { }