[GIT PULL] x86/cpu tree change for v3.18

From: Ingo Molnar
Date: Mon Oct 13 2014 - 03:29:10 EST


Linus,

Please pull the latest x86-cpu-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-cpu-for-linus

# HEAD: 2ed53c0d6cc99fc712f7c037e41d9ec4eb8d6b08 x86/smpboot: Speed up suspend/resume by avoiding 100ms sleep for CPU offline during S3

This tree includes a single commit that speeds up x86
suspend/resume by replacing a naive 100msec sleep based
polling loop with proper completion notification.

This gives some real suspend/resume benefit on servers
with larger core counts.

Thanks,

Ingo

------------------>
Lan Tianyu (1):
x86/smpboot: Speed up suspend/resume by avoiding 100ms sleep for CPU offline during S3


arch/x86/kernel/smpboot.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 2d872e08fab9..fdbc5fce8b97 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -102,6 +102,8 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
DEFINE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
EXPORT_PER_CPU_SYMBOL(cpu_info);

+static DEFINE_PER_CPU(struct completion, die_complete);
+
atomic_t init_deasserted;

/*
@@ -1323,26 +1325,24 @@ int native_cpu_disable(void)
return ret;

clear_local_APIC();
-
+ init_completion(&per_cpu(die_complete, smp_processor_id()));
cpu_disable_common();
+
return 0;
}

void native_cpu_die(unsigned int cpu)
{
/* We don't do anything here: idle task is faking death itself. */
- unsigned int i;
+ wait_for_completion_timeout(&per_cpu(die_complete, cpu), HZ);

- for (i = 0; i < 10; i++) {
- /* They ack this in play_dead by setting CPU_DEAD */
- if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
- if (system_state == SYSTEM_RUNNING)
- pr_info("CPU %u is now offline\n", cpu);
- return;
- }
- msleep(100);
+ /* They ack this in play_dead() by setting CPU_DEAD */
+ if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
+ if (system_state == SYSTEM_RUNNING)
+ pr_info("CPU %u is now offline\n", cpu);
+ } else {
+ pr_err("CPU %u didn't die...\n", cpu);
}
- pr_err("CPU %u didn't die...\n", cpu);
}

void play_dead_common(void)
@@ -1354,6 +1354,7 @@ void play_dead_common(void)
mb();
/* Ack it */
__this_cpu_write(cpu_state, CPU_DEAD);
+ complete(&per_cpu(die_complete, smp_processor_id()));

/*
* With physical CPU hotplug, we should halt the cpu
--
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