From: Frederic Weisbecker <frederic@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Chris Metcalf <cmetcalf@mellanox.com>,
Thomas Gleixner <tglx@linutronix.de>,
Luiz Capitulino <lcapitulino@redhat.com>,
Christoph Lameter <cl@linux.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>, Wanpeng Li <kernellwp@gmail.com>,
Mike Galbraith <efault@gmx.de>, Rik van Riel <riel@redhat.com>
Subject: [PATCH 3/7] nohz: Allow to check if remote CPU tick is stopped
Date: Wed, 21 Feb 2018 05:17:25 +0100 [thread overview]
Message-ID: <1519186649-3242-4-git-send-email-frederic@kernel.org> (raw)
In-Reply-To: <1519186649-3242-1-git-send-email-frederic@kernel.org>
This check is racy but provides a good heuristic to determine whether
a CPU may need a remote tick or not.
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
---
include/linux/tick.h | 2 ++
kernel/time/tick-sched.c | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/include/linux/tick.h b/include/linux/tick.h
index 86576d9..7f8c9a12 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -114,6 +114,7 @@ enum tick_dep_bits {
#ifdef CONFIG_NO_HZ_COMMON
extern bool tick_nohz_enabled;
extern bool tick_nohz_tick_stopped(void);
+extern bool tick_nohz_tick_stopped_cpu(int cpu);
extern void tick_nohz_idle_enter(void);
extern void tick_nohz_idle_exit(void);
extern void tick_nohz_irq_exit(void);
@@ -125,6 +126,7 @@ extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
#else /* !CONFIG_NO_HZ_COMMON */
#define tick_nohz_enabled (0)
static inline int tick_nohz_tick_stopped(void) { return 0; }
+static inline int tick_nohz_tick_stopped_cpu(int cpu) { return 0; }
static inline void tick_nohz_idle_enter(void) { }
static inline void tick_nohz_idle_exit(void) { }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0aba041..d479b21 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -486,6 +486,13 @@ bool tick_nohz_tick_stopped(void)
return __this_cpu_read(tick_cpu_sched.tick_stopped);
}
+bool tick_nohz_tick_stopped_cpu(int cpu)
+{
+ struct tick_sched *ts = per_cpu_ptr(&tick_cpu_sched, cpu);
+
+ return ts->tick_stopped;
+}
+
/**
* tick_nohz_update_jiffies - update jiffies when idle was interrupted
*
--
2.7.4
next prev parent reply other threads:[~2018-02-21 4:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-21 4:17 [PATCH 0/7] isolation: 1Hz residual tick offloading v7 Frederic Weisbecker
2018-02-21 4:17 ` [PATCH 1/7] sched: Rename init_rq_hrtick to hrtick_rq_init Frederic Weisbecker
2018-02-21 10:35 ` [tip:sched/core] sched/core: Rename init_rq_hrtick() to hrtick_rq_init() tip-bot for Frederic Weisbecker
2018-02-21 4:17 ` [PATCH 2/7] nohz: Convert tick_nohz_tick_stopped() to bool Frederic Weisbecker
2018-02-21 8:29 ` Thomas Gleixner
2018-02-21 10:35 ` [tip:sched/core] " tip-bot for Frederic Weisbecker
2018-02-21 4:17 ` Frederic Weisbecker [this message]
2018-02-21 10:36 ` [tip:sched/core] nohz: Allow to check if remote CPU tick is stopped tip-bot for Frederic Weisbecker
2018-02-21 4:17 ` [PATCH 4/7] sched/isolation: Isolate workqueues when "nohz_full=" is set Frederic Weisbecker
2018-02-21 10:36 ` [tip:sched/core] " tip-bot for Frederic Weisbecker
2018-02-21 4:17 ` [PATCH 5/7] sched/isolation: Offload residual 1Hz scheduler tick Frederic Weisbecker
2018-02-21 10:37 ` [tip:sched/core] " tip-bot for Frederic Weisbecker
2018-02-21 4:17 ` [PATCH 6/7] sched/nohz: Remove the 1 Hz tick code Frederic Weisbecker
2018-02-21 10:37 ` [tip:sched/core] " tip-bot for Frederic Weisbecker
2018-02-21 4:17 ` [PATCH 7/7] sched/isolation: Update nohz documentation to explain tick offload Frederic Weisbecker
2018-02-21 8:30 ` Thomas Gleixner
2018-02-21 10:38 ` [tip:sched/core] " tip-bot for Frederic Weisbecker
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