From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Peter Anvin <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
linux-arch@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Arjan van de Ven <arjan@linux.intel.com>,
Rik van Riel <riel@redhat.com>,
"Srivatsa S. Bhat" <srivatsa@mit.edu>,
Sebastian Siewior <bigeasy@linutronix.de>,
Paul Turner <pjt@google.com>
Subject: [patch 19/20] cpu/hotplug: Make wait for dead cpu completion based
Date: Fri, 26 Feb 2016 18:43:43 -0000 [thread overview]
Message-ID: <20160226182341.776157858@linutronix.de> (raw)
In-Reply-To: 20160226164321.657646833@linutronix.de
[-- Attachment #1: hotplug--Make-wait-for-dead-cpu-completion-based.patch --]
[-- Type: text/plain, Size: 3225 bytes --]
Kill the busy spinning on the control side and just wait for the hotplugged
cpu to tell that it reached the dead state.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/cpu.h | 5 +++--
include/linux/cpuhotplug.h | 1 +
kernel/cpu.c | 16 ++++++++++++----
kernel/sched/idle.c | 5 +----
4 files changed, 17 insertions(+), 10 deletions(-)
Index: b/include/linux/cpu.h
===================================================================
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -276,14 +276,15 @@ void arch_cpu_idle_enter(void);
void arch_cpu_idle_exit(void);
void arch_cpu_idle_dead(void);
-DECLARE_PER_CPU(bool, cpu_dead_idle);
-
int cpu_report_state(int cpu);
int cpu_check_up_prepare(int cpu);
void cpu_set_state_online(int cpu);
#ifdef CONFIG_HOTPLUG_CPU
bool cpu_wait_death(unsigned int cpu, int seconds);
bool cpu_report_death(void);
+void cpuhp_report_idle_dead(void);
+#else
+static inline void cpuhp_report_idle_dead(void) { }
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
#endif /* _LINUX_CPU_H_ */
Index: b/include/linux/cpuhotplug.h
===================================================================
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -6,6 +6,7 @@ enum cpuhp_state {
CPUHP_CREATE_THREADS,
CPUHP_NOTIFY_PREPARE,
CPUHP_BRINGUP_CPU,
+ CPUHP_AP_IDLE_DEAD,
CPUHP_AP_OFFLINE,
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,
Index: b/kernel/cpu.c
===================================================================
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -688,6 +688,7 @@ static int take_cpu_down(void *_param)
static int takedown_cpu(unsigned int cpu)
{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int err;
/*
@@ -733,10 +734,8 @@ static int takedown_cpu(unsigned int cpu
*
* Wait for the stop thread to go away.
*/
- while (!per_cpu(cpu_dead_idle, cpu))
- cpu_relax();
- smp_mb(); /* Read from cpu_dead_idle before __cpu_die(). */
- per_cpu(cpu_dead_idle, cpu) = false;
+ wait_for_completion(&st->done);
+ BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
/* Interrupts are moved away from the dying cpu, reenable alloc/free */
irq_unlock_sparse();
@@ -756,6 +755,15 @@ static int notify_dead(unsigned int cpu)
return 0;
}
+void cpuhp_report_idle_dead(void)
+{
+ struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
+
+ BUG_ON(st->state != CPUHP_AP_OFFLINE);
+ st->state = CPUHP_AP_IDLE_DEAD;
+ complete(&st->done);
+}
+
#else
#define notify_down_prepare NULL
#define takedown_cpu NULL
Index: b/kernel/sched/idle.c
===================================================================
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -194,8 +194,6 @@ static void cpuidle_idle_call(void)
rcu_idle_exit();
}
-DEFINE_PER_CPU(bool, cpu_dead_idle);
-
/*
* Generic idle loop implementation
*
@@ -224,8 +222,7 @@ static void cpu_idle_loop(void)
if (cpu_is_offline(smp_processor_id())) {
rcu_cpu_notify(NULL, CPU_DYING_IDLE,
(void *)(long)smp_processor_id());
- smp_mb(); /* all activity before dead. */
- this_cpu_write(cpu_dead_idle, true);
+ cpuhp_report_idle_dead();
arch_cpu_idle_dead();
}
next prev parent reply other threads:[~2016-02-26 18:45 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-26 18:43 [patch 00/20] cpu/hotplug: Core infrastructure for cpu hotplug rework Thomas Gleixner
2016-02-26 18:43 ` [patch 01/20] idle: Move x86ism out of generic code Thomas Gleixner
2016-02-27 20:29 ` Brian Gerst
2016-02-29 19:35 ` Thomas Gleixner
2016-02-29 19:48 ` Will Deacon
2016-02-29 20:06 ` Thomas Gleixner
2016-02-26 18:43 ` [patch 02/20] cpu/hotplug: Restructure FROZEN state handling Thomas Gleixner
2016-03-01 19:51 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 22:35 ` Srivatsa S. Bhat
2016-03-02 23:43 ` Srivatsa S. Bhat
2016-02-26 18:43 ` [patch 03/20] cpu/hotplug: Restructure cpu_up code Thomas Gleixner
2016-03-01 19:52 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 22:36 ` Srivatsa S. Bhat
2016-02-26 18:43 ` [patch 04/20] cpu/hotplug: Split out cpu down functions Thomas Gleixner
2016-03-01 19:52 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 22:37 ` Srivatsa S. Bhat
2016-02-26 18:43 ` [patch 05/20] cpu/hotplug: Add tracepoints Thomas Gleixner
2016-03-01 19:52 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 06/20] cpu/hotplug: Convert to a state machine for the control processor Thomas Gleixner
2016-03-01 19:53 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 11:23 ` Peter Zijlstra
2016-02-26 18:43 ` [patch 07/20] cpu/hotplug: Convert the hotplugged cpu work to a state machine Thomas Gleixner
2016-03-01 19:53 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 08/20] cpu/hotplug: Hand in target state to _cpu_up/down Thomas Gleixner
2016-03-01 19:54 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 09/20] cpu/hotplug: Add sysfs state interface Thomas Gleixner
2016-03-01 19:54 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 12:40 ` Peter Zijlstra
2016-02-26 18:43 ` [patch 10/20] cpu/hotplug: Make target state writeable Thomas Gleixner
2016-02-26 23:46 ` Rafael J. Wysocki
2016-02-27 7:39 ` Thomas Gleixner
2016-02-27 14:43 ` Rafael J. Wysocki
2016-02-28 14:49 ` Thomas Gleixner
2016-02-29 15:49 ` Thomas Gleixner
2016-03-01 1:53 ` Rafael J. Wysocki
2016-03-01 19:55 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 12:41 ` Peter Zijlstra
2016-03-02 19:57 ` Thomas Gleixner
2016-02-26 18:43 ` [patch 11/20] cpu/hotplug: Implement setup/removal interface Thomas Gleixner
2016-03-01 19:55 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 12/20] cpu/hotplug: Move scheduler cpu_online notifier to hotplug core Thomas Gleixner
2016-03-01 19:55 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 13/20] cpu/hotplug: Unpark smpboot threads from the state machine Thomas Gleixner
2016-03-01 19:56 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 14/20] cpu/hotplug: Split out the state walk into functions Thomas Gleixner
2016-03-01 19:56 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 15/20] cpu/hotplug: Create hotplug threads Thomas Gleixner
2016-03-01 19:57 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 16/20] cpu/hotplug: Move online calls to hotplugged cpu Thomas Gleixner
2016-03-01 19:57 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 17/20] arch/hotplug: Call into idle with a proper state Thomas Gleixner
2016-03-01 19:57 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 18/20] cpu/hotplug: Let upcoming cpu bring itself fully up Thomas Gleixner
2016-03-01 19:58 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 17:28 ` [patch 18/20] " Richard Cochran
2016-02-26 18:43 ` Thomas Gleixner [this message]
2016-03-01 19:58 ` [tip:smp/hotplug] cpu/hotplug: Make wait for dead cpu completion based tip-bot for Thomas Gleixner
2016-02-26 18:43 ` [patch 20/20] rcu: Make CPU_DYING_IDLE an explicit call Thomas Gleixner
2016-02-27 2:14 ` Paul E. McKenney
2016-02-27 2:23 ` Paul E. McKenney
2016-02-27 7:47 ` Thomas Gleixner
2016-02-27 11:05 ` Paul E. McKenney
2016-02-27 11:30 ` Thomas Gleixner
2016-02-27 16:33 ` Paul E. McKenney
2016-03-01 19:58 ` [tip:smp/hotplug] " tip-bot for Thomas Gleixner
2016-03-02 20:11 ` Paul E. McKenney
2016-03-03 7:31 ` Thomas Gleixner
2016-03-03 10:03 ` [tip:smp/hotplug] cpu/hotplug: Plug death reporting race tip-bot for Thomas Gleixner
2016-03-03 14:11 ` Paul E. McKenney
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