Re: [PATCH 5/7] irq_work: Don't stop the tick with pending works
2012/11/15 Steven Rostedt :
> On Wed, 2012-11-14 at 21:37 +0100, Frederic Weisbecker wrote:
>> diff --git a/kernel/irq_work.c b/kernel/irq_work.c
>> index 64eddd5..b3c113a 100644
>> --- a/kernel/irq_work.c
>> +++ b/kernel/irq_work.c
>> @@ -99,6 +99,17 @@ bool irq_work_queue(struct irq_work *work)
>> }
>> EXPORT_SYMBOL_GPL(irq_work_queue);
>>
>> +bool irq_work_needs_cpu(void)
>> +{
>> + struct llist_head *this_list;
>> +
>> + this_list = &__get_cpu_var(irq_work_list);
>> + if (llist_empty(this_list))
>> + return false;
>> +
>
> I wounder if this should just be:
>
> return !llist_empty(_cpu_read(irq_work_list));
Yeah I'll simplify that way.
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Re: [PATCH 5/7] irq_work: Don't stop the tick with pending works
2012/11/15 Steven Rostedt rost...@goodmis.org:
On Wed, 2012-11-14 at 21:37 +0100, Frederic Weisbecker wrote:
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 64eddd5..b3c113a 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -99,6 +99,17 @@ bool irq_work_queue(struct irq_work *work)
}
EXPORT_SYMBOL_GPL(irq_work_queue);
+bool irq_work_needs_cpu(void)
+{
+ struct llist_head *this_list;
+
+ this_list = __get_cpu_var(irq_work_list);
+ if (llist_empty(this_list))
+ return false;
+
I wounder if this should just be:
return !llist_empty(this_cpu_read(irq_work_list));
Yeah I'll simplify that way.
--
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Re: [PATCH 5/7] irq_work: Don't stop the tick with pending works
On Wed, 2012-11-14 at 21:37 +0100, Frederic Weisbecker wrote:
> Don't stop the tick if we have pending irq works on the
> queue, otherwise if the arch can't raise self-IPIs, we may not
> find an opportunity to execute the pending works for a while.
>
> Signed-off-by: Frederic Weisbecker
> Cc: Peter Zijlstra
> Cc: Thomas Gleixner
> Cc: Ingo Molnar
> Cc: Andrew Morton
> Cc: Steven Rostedt
> Cc: Paul Gortmaker
> ---
> include/linux/irq_work.h |6 ++
> kernel/irq_work.c| 11 +++
> kernel/time/tick-sched.c |3 ++-
> 3 files changed, 19 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
> index 6a9e8f5..a69704f 100644
> --- a/include/linux/irq_work.h
> +++ b/include/linux/irq_work.h
> @@ -20,4 +20,10 @@ bool irq_work_queue(struct irq_work *work);
> void irq_work_run(void);
> void irq_work_sync(struct irq_work *work);
>
> +#ifdef CONFIG_IRQ_WORK
> +bool irq_work_needs_cpu(void);
> +#else
> +static bool irq_work_needs_cpu(void) { return false; }
> +#endif
> +
> #endif /* _LINUX_IRQ_WORK_H */
> diff --git a/kernel/irq_work.c b/kernel/irq_work.c
> index 64eddd5..b3c113a 100644
> --- a/kernel/irq_work.c
> +++ b/kernel/irq_work.c
> @@ -99,6 +99,17 @@ bool irq_work_queue(struct irq_work *work)
> }
> EXPORT_SYMBOL_GPL(irq_work_queue);
>
> +bool irq_work_needs_cpu(void)
> +{
> + struct llist_head *this_list;
> +
> + this_list = &__get_cpu_var(irq_work_list);
> + if (llist_empty(this_list))
> + return false;
> +
I wounder if this should just be:
return !llist_empty(_cpu_read(irq_work_list));
-- Steve
> + return true;
> +}
> +
> /*
> * Run the irq_work entries on this cpu. Requires to be ran from hardirq
> * context with local IRQs disabled.
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 9e945aa..f249e8c 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -20,6 +20,7 @@
> #include
> #include
> #include
> +#include
>
> #include
>
> @@ -289,7 +290,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct
> tick_sched *ts,
> } while (read_seqretry(_lock, seq));
>
> if (rcu_needs_cpu(cpu, _delta_jiffies) || printk_needs_cpu(cpu) ||
> - arch_needs_cpu(cpu)) {
> + arch_needs_cpu(cpu) || irq_work_needs_cpu()) {
> next_jiffies = last_jiffies + 1;
> delta_jiffies = 1;
> } else {
--
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Re: [PATCH 5/7] irq_work: Don't stop the tick with pending works
On Wed, 2012-11-14 at 21:37 +0100, Frederic Weisbecker wrote:
Don't stop the tick if we have pending irq works on the
queue, otherwise if the arch can't raise self-IPIs, we may not
find an opportunity to execute the pending works for a while.
Signed-off-by: Frederic Weisbecker fweis...@gmail.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Thomas Gleixner t...@linutronix.de
Cc: Ingo Molnar mi...@kernel.org
Cc: Andrew Morton a...@linux-foundation.org
Cc: Steven Rostedt rost...@goodmis.org
Cc: Paul Gortmaker paul.gortma...@windriver.com
---
include/linux/irq_work.h |6 ++
kernel/irq_work.c| 11 +++
kernel/time/tick-sched.c |3 ++-
3 files changed, 19 insertions(+), 1 deletions(-)
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
index 6a9e8f5..a69704f 100644
--- a/include/linux/irq_work.h
+++ b/include/linux/irq_work.h
@@ -20,4 +20,10 @@ bool irq_work_queue(struct irq_work *work);
void irq_work_run(void);
void irq_work_sync(struct irq_work *work);
+#ifdef CONFIG_IRQ_WORK
+bool irq_work_needs_cpu(void);
+#else
+static bool irq_work_needs_cpu(void) { return false; }
+#endif
+
#endif /* _LINUX_IRQ_WORK_H */
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 64eddd5..b3c113a 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -99,6 +99,17 @@ bool irq_work_queue(struct irq_work *work)
}
EXPORT_SYMBOL_GPL(irq_work_queue);
+bool irq_work_needs_cpu(void)
+{
+ struct llist_head *this_list;
+
+ this_list = __get_cpu_var(irq_work_list);
+ if (llist_empty(this_list))
+ return false;
+
I wounder if this should just be:
return !llist_empty(this_cpu_read(irq_work_list));
-- Steve
+ return true;
+}
+
/*
* Run the irq_work entries on this cpu. Requires to be ran from hardirq
* context with local IRQs disabled.
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 9e945aa..f249e8c 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -20,6 +20,7 @@
#include linux/profile.h
#include linux/sched.h
#include linux/module.h
+#include linux/irq_work.h
#include asm/irq_regs.h
@@ -289,7 +290,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct
tick_sched *ts,
} while (read_seqretry(xtime_lock, seq));
if (rcu_needs_cpu(cpu, rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
- arch_needs_cpu(cpu)) {
+ arch_needs_cpu(cpu) || irq_work_needs_cpu()) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {
--
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