Re: [RFC PATCH v2 3/7] sched/idle: Add poll before enter real idle path
From: Quan Xu
Date: Fri Sep 29 2017 - 06:41:02 EST
On 2017/9/1 14:49, Quan Xu wrote:
on 2017/8/29 22:39, Borislav Petkov wrote:
On Tue, Aug 29, 2017 at 11:46:37AM +0000, Yang Zhang wrote:
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@xxxxxxxxx>
Signed-off-by: Quan Xu <quan.xu0@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Kyle Huey <me@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 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)
ÂÂÂÂÂ x86_idle();
 }
 +#if defined(CONFIG_SMP) && defined(CONFIG_PARAVIRT)
+void arch_cpu_idle_poll(void)
+{
+ÂÂÂ paravirt_idle_poll();
+}
+#endif
So this will get called on any system which has CONFIG_PARAVIRT enabled
*even* if they're not running any guests.
Huh?
ÂÂÂÂ Borislav,
ÂÂÂÂ think twice, it is better to run ander an IF condition, to make
sure they are running any guests.
ÂÂÂÂÂ Quan
Borislav ,
ÂÂ yes, this will get called on any system which has CONFIG_PARAVIRT
enabled.
 but if they are not running any guests, the callback is
paravirt_nop() ,
ÂÂ IIUC which is as similar as the other paravirt_*, such as
paravirt_pgd_free()..
Â- Quan