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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-01-28 23:09:43 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-03-12 23:19:37 +0100 |
| commit | 528a25b00e1f84eaba6c98e63f58ee0a8e472102 (patch) | |
| tree | 449e267d06f42020bcaaae7a218710112bedd38e /kernel/sched | |
| parent | rcu: Eliminate ->onoff_mutex from rcu_node structure (diff) | |
| download | linux-528a25b00e1f84eaba6c98e63f58ee0a8e472102.tar.xz linux-528a25b00e1f84eaba6c98e63f58ee0a8e472102.zip | |
cpu: Make CPU-offline idle-loop transition point more precise
This commit uses a per-CPU variable to make the CPU-offline code path
through the idle loop more precise, so that the outgoing CPU is
guaranteed to make it into the idle loop before it is powered off.
This commit is in preparation for putting the RCU offline-handling
code on this code path, which will eliminate the magic one-jiffy
wait that RCU uses as the maximum time for an outgoing CPU to get
all the way through the scheduler.
The magic one-jiffy wait for incoming CPUs remains a separate issue.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/idle.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 94b2d7b88a27..e99e361ade20 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -198,6 +198,8 @@ exit_idle: start_critical_timings(); } +DEFINE_PER_CPU(bool, cpu_dead_idle); + /* * Generic idle loop implementation * @@ -222,8 +224,11 @@ static void cpu_idle_loop(void) check_pgt_cache(); rmb(); - if (cpu_is_offline(smp_processor_id())) + if (cpu_is_offline(smp_processor_id())) { + smp_mb(); /* all activity before dead. */ + this_cpu_write(cpu_dead_idle, true); arch_cpu_idle_dead(); + } local_irq_disable(); arch_cpu_idle_enter(); |