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

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Date:   Tue, 29 Aug 2017 11:46:37 +0000
From:   Yang Zhang <yang.zhang.wz@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     kvm@...r.kernel.org, wanpeng.li@...mail.com, mst@...hat.com,
        pbonzini@...hat.com, tglx@...utronix.de, rkrcmar@...hat.com,
        dmatlack@...gle.com, agraf@...e.de, peterz@...radead.org,
        linux-doc@...r.kernel.org, Yang Zhang <yang.zhang.wz@...il.com>,
        Quan Xu <quan.xu0@...il.com>, Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Borislav Petkov <bp@...en8.de>, Kyle Huey <me@...ehuey.com>,
        Andy Lutomirski <luto@...nel.org>,
        Len Brown <len.brown@...el.com>
Subject: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path

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@...il.com>
Signed-off-by: Quan Xu <quan.xu0@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Kyle Huey <me@...ehuey.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Len Brown <len.brown@...el.com>
Cc: linux-kernel@...r.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