Commit-ID: 07f06cb3b5f6bd21374a48dbefdb431d71d53974
Gitweb: http://git.kernel.org/tip/07f06cb3b5f6bd21374a48dbefdb431d71d53974
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 9 Oct 2015 18:00:54 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 20 Oct 2015 10:25:55 +0200
sched: Start stopper early
Ensure the stopper thread is active 'early', because the load balancer
pretty much assumes that its available. And when 'online && active' the
load-balancer is fully available.
Not only the numa balancing stop_two_cpus() caller relies on it, but
also the self migration stuff does, and at CPU_ONLINE time the cpu
really is 'free' to run anything.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: heiko.carstens@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20151009160054.GA10176@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/cpu.c | 1 -
kernel/sched/core.c | 12 +++++++++---
2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6467521..c85df27 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -475,7 +475,6 @@ static int smpboot_thread_call(struct notifier_block *nfb,
case CPU_DOWN_FAILED:
case CPU_ONLINE:
- stop_machine_unpark(cpu);
smpboot_unpark_threads(cpu);
break;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f45a7c7..7ee8cae 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5545,21 +5545,27 @@ static void set_cpu_rq_start_time(void)
static int sched_cpu_active(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
+ int cpu = (long)hcpu;
+
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_STARTING:
set_cpu_rq_start_time();
return NOTIFY_OK;
+
case CPU_ONLINE:
/*
* At this point a starting CPU has marked itself as online via
* set_cpu_online(). But it might not yet have marked itself
* as active, which is essential from here on.
- *
- * Thus, fall-through and help the starting CPU along.
*/
+ set_cpu_active(cpu, true);
+ stop_machine_unpark(cpu);
+ return NOTIFY_OK;
+
case CPU_DOWN_FAILED:
- set_cpu_active((long)hcpu, true);
+ set_cpu_active(cpu, true);
return NOTIFY_OK;
+
default:
return NOTIFY_DONE;
}
--
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