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authorPeter Zijlstra <peterz@infradead.org>2011-12-15 17:09:22 +0100
committerIngo Molnar <mingo@elte.hu>2012-03-12 20:43:15 +0100
commit5fbd036b552f633abb394a319f7c62a5c86a9cd7 (patch)
treefa91474a6aac5ea4aef0d7afc72af27c32d611af /arch/hexagon/kernel
parent5d6523ebd2f67de9d23285aad7f3910e7b0aee83 (diff)
downloadvexpress-lsk-5fbd036b552f633abb394a319f7c62a5c86a9cd7.tar.gz
sched: Cleanup cpu_active madness
Stepan found: CPU0 CPUn _cpu_up() __cpu_up() boostrap() notify_cpu_starting() set_cpu_online() while (!cpu_active()) cpu_relax() <PREEMPT-out> smp_call_function(.wait=1) /* we find cpu_online() is true */ arch_send_call_function_ipi_mask() /* wait-forever-more */ <PREEMPT-in> local_irq_enable() cpu_notify(CPU_ONLINE) sched_cpu_active() set_cpu_active() Now the purpose of cpu_active is mostly with bringing down a cpu, where we mark it !active to avoid the load-balancer from moving tasks to it while we tear down the cpu. This is required because we only update the sched_domain tree after we brought the cpu-down. And this is needed so that some tasks can still run while we bring it down, we just don't want new tasks to appear. On cpu-up however the sched_domain tree doesn't yet include the new cpu, so its invisible to the load-balancer, regardless of the active state. So instead of setting the active state after we boot the new cpu (and consequently having to wait for it before enabling interrupts) set the cpu active before we set it online and avoid the whole mess. Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1323965362.18942.71.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/hexagon/kernel')
-rw-r--r--arch/hexagon/kernel/smp.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c
index c871a2cffae..0123c63e9a3 100644
--- a/arch/hexagon/kernel/smp.c
+++ b/arch/hexagon/kernel/smp.c
@@ -179,8 +179,6 @@ void __cpuinit start_secondary(void)
printk(KERN_INFO "%s cpu %d\n", __func__, current_thread_info()->cpu);
set_cpu_online(cpu, true);
- while (!cpumask_test_cpu(cpu, cpu_active_mask))
- cpu_relax();
local_irq_enable();
cpu_idle();