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authorPeter Zijlstra <peterz@infradead.org>2015-10-09 18:00:54 +0200
committerIngo Molnar <mingo@kernel.org>2015-10-20 10:25:55 +0200
commit07f06cb3b5f6bd21374a48dbefdb431d71d53974 (patch)
tree80eafc844814f3a7fbc64191e1721a39f59aec37 /kernel
parentf0cf16cbd0659d2dd21352da9f06f3fab7a51596 (diff)
downloadop-kernel-dev-07f06cb3b5f6bd21374a48dbefdb431d71d53974.zip
op-kernel-dev-07f06cb3b5f6bd21374a48dbefdb431d71d53974.tar.gz
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@infradead.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> 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: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: heiko.carstens@de.ibm.com Link: http://lkml.kernel.org/r/20151009160054.GA10176@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpu.c1
-rw-r--r--kernel/sched/core.c12
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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