cpuidle-haltpoll: Replace default_idle() with arch_cpu_idle()

When a KVM guest has MWAIT, mwait_idle() is used as the default idle
function.

However, the cpuidle-haltpoll driver calls default_idle() from
default_enter_idle() directly and that one uses HLT instead of MWAIT,
which may affect performance adversely, because MWAIT is preferred to
HLT as explained by the changelog of commit aebef63cf7ff ("x86: Remove
vendor checks from prefer_mwait_c1_over_halt").

Make default_enter_idle() call arch_cpu_idle(), which can use MWAIT,
instead of default_idle() to address this issue.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
[ rjw: Changelog rewrite ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 40d156a..00a831d 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -721,6 +721,7 @@ void arch_cpu_idle(void)
 {
        x86_idle();
 }
+EXPORT_SYMBOL_GPL(arch_cpu_idle);
 
 /*
  * We use this if we don't have any better idle routine..

diff --git a/drivers/cpuidle/cpuidle-haltpoll.c b/drivers/cpuidle/cpuidle-haltpoll.c
index 3a39a7f..e66df22 100644 (file)
--- a/drivers/cpuidle/cpuidle-haltpoll.c
+++ b/drivers/cpuidle/cpuidle-haltpoll.c
@@ -32,7 +32,7 @@ static int default_enter_idle(struct cpuidle_device *dev,
                local_irq_enable();
                return index;
        }
-       default_idle();
+       arch_cpu_idle();
        return index;
 }