From: Yang Zhang <[email protected]> Implement a generic idle poll which resembles the functionality found in arch/. Provide weak arch_cpu_idle_poll function which can be overridden by the architecture code if needed.
Interrupts arrive which may not cause a reschedule in idle loops. In KVM guest, this costs several VM-exit/VM-entry cycles, VM-entry for interrupts and VM-exit immediately. Also this becomes more expensive than bare metal. Add a generic idle poll before enter real idle path. When a reschedule event is pending, we can bypass the real idle path. Signed-off-by: Quan Xu <[email protected]> Signed-off-by: Yang Zhang <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: [email protected] Cc: Peter Zijlstra <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Kyle Huey <[email protected]> Cc: Len Brown <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Tom Lendacky <[email protected]> Cc: Tobias Klauser <[email protected]> Cc: [email protected] --- arch/x86/kernel/process.c | 7 +++++++ kernel/sched/idle.c | 2 ++ 2 files changed, 9 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index c676853..f7db8b5 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -333,6 +333,13 @@ void arch_cpu_idle(void) x86_idle(); } +#ifdef 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 257f4f0..df7c422 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(); -- 1.7.1 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
