On Wed, May 04, 2011 at 04:31:03PM +0300, Gleb Natapov wrote:
> Provide rcu_virt_note_context_switch() for vitalization use to note
> quiescent state during guest entry.
Very good, queued on -rcu.
Unless you tell me otherwise, I will assume that you want to carry the
patch modifying KVM to use this.
Thanx, Paul
> Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
> ---
> include/linux/rcutiny.h | 8 ++++++++
> include/linux/rcutree.h | 10 ++++++++++
> kernel/rcutree.c | 1 +
> 3 files changed, 19 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
> index 30ebd7c..52b3e02 100644
> --- a/include/linux/rcutiny.h
> +++ b/include/linux/rcutiny.h
> @@ -100,6 +100,14 @@ static inline void rcu_note_context_switch(int cpu)
> }
>
> /*
> + * Take advantage of the fact that there is only one CPU, which
> + * allows us to ignore virtualization-based context switches.
> + */
> +static inline void rcu_virt_note_context_switch(int cpu)
> +{
> +}
> +
> +/*
> * Return the number of grace periods.
> */
> static inline long rcu_batches_completed(void)
> diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
> index 3a93348..b2a906e 100644
> --- a/include/linux/rcutree.h
> +++ b/include/linux/rcutree.h
> @@ -35,6 +35,16 @@ extern void rcu_note_context_switch(int cpu);
> extern int rcu_needs_cpu(int cpu);
> extern void rcu_cpu_stall_reset(void);
>
> +/*
> + * Note a virtualization-based context switch. This is simply a
> + * wrapper around rcu_note_context_switch(), which allows TINY_RCU
> + * to save a few bytes.
> + */
> +static inline void rcu_virt_note_context_switch(int cpu)
> +{
> + rcu_note_context_switch(cpu);
> +}
> +
> #ifdef CONFIG_TREE_PREEMPT_RCU
>
> extern void exit_rcu(void);
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index dd4aea8..0837d63 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -124,6 +124,7 @@ void rcu_note_context_switch(int cpu)
> rcu_sched_qs(cpu);
> rcu_preempt_note_context_switch(cpu);
> }
> +EXPORT_SYMBOL_GPL(rcu_note_context_switch);
>
> #ifdef CONFIG_NO_HZ
> DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
> --
> 1.7.4.4
>
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