Commit 716ff71a authored by Li RongQing's avatar Li RongQing Committed by Rafael J. Wysocki
Browse files

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 aebef63c ("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: default avatarThomas Gleixner <tglx@linutronix.de>
Suggested-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarLi RongQing <lirongqing@baidu.com>
[ rjw: Changelog rewrite ]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 4edc13ae

arch/x86/kernel/process.c

+1 −0
Original line number Diff line number Diff line
@@ -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..

drivers/cpuidle/cpuidle-haltpoll.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

}