[RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path

Yang Zhang
2017-08-29T11:47:31Z

Add poll in do_idle. For UP VM, if there are running task, it will not
goes into idle path, so we only enable poll in SMP VM.

Signed-off-by: Yang Zhang <yang.zhang.wz@gmail.com>
Signed-off-by: Quan Xu <quan.xu0@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kyle Huey <me@kylehuey.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: linux-kernel@vger.kernel.org
---
arch/x86/kernel/process.c | 7 +++++++
kernel/sched/idle.c | 2 ++
2 files changed, 9 insertions(+)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 3ca1980..def4113 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -332,6 +332,13 @@ void arch_cpu_idle(void)
x86_idle();
}

+#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT)
+void arch_cpu_idle_poll(void)
+{
+ paravirt_idle_poll();
+}
+#endif
+
/*
* We use this if we don't have any better idle routine..
*/
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 6c23e30..b374744 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -74,6 +74,7 @@ static noinline int __cpuidle cpu_idle_poll(void)
}

/* Weak implementations for optional arch specific functions */
+void __weak arch_cpu_idle_poll(void) { }
void __weak arch_cpu_idle_prepare(void) { }
void __weak arch_cpu_idle_enter(void) { }
void __weak arch_cpu_idle_exit(void) { }
@@ -219,6 +220,7 @@ static void do_idle(void)
*/

__current_set_polling();
+ arch_cpu_idle_poll();
quiet_vmstat();
tick_nohz_idle_enter();

--
1.8.3.1