[PATCH] clocksource/drivers/tegra: allow timer irq affinity change

[PATCH] clocksource/drivers/tegra: allow timer irq affinity change

[Lucas Stach]

Allow the timer core to change the smp affinity of the broadcast timer
irq by setting CLOCK_EVT_FEAT_DYNIRQ flag.

This reduces interrupt pressure and wakeups on CPU0 as well as vastly
reducing the number of timer broadcast IPIs.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
 drivers/clocksource/tegra20_timer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/tegra20_timer.c b/drivers/clocksource/tegra20_timer.c
index 6ebda11..38333ab 100644
--- a/drivers/clocksource/tegra20_timer.c
+++ b/drivers/clocksource/tegra20_timer.c
@@ -96,7 +96,8 @@ static struct clock_event_device tegra_clockevent = {
 	.name			= "timer0",
 	.rating			= 300,
 	.features		= CLOCK_EVT_FEAT_ONESHOT |
-				  CLOCK_EVT_FEAT_PERIODIC,
+				  CLOCK_EVT_FEAT_PERIODIC |
+				  CLOCK_EVT_FEAT_DYNIRQ,
 	.set_next_event		= tegra_timer_set_next_event,
 	.set_state_shutdown	= tegra_timer_shutdown,
 	.set_state_periodic	= tegra_timer_set_periodic,
-- 
2.4.3

Re: [PATCH] clocksource/drivers/tegra: allow timer irq affinity change

[Daniel Lezcano]

On 10/25/2015 04:40 PM, Lucas Stach wrote:
> Allow the timer core to change the smp affinity of the broadcast timer
> irq by setting CLOCK_EVT_FEAT_DYNIRQ flag.
>
> This reduces interrupt pressure and wakeups on CPU0 as well as vastly
> reducing the number of timer broadcast IPIs.

Did you test this patch on a tegra2 ?



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Re: [PATCH] clocksource/drivers/tegra: allow timer irq affinity change

[Lucas Stach]

Am Dienstag, den 27.10.2015, 11:14 +0100 schrieb Daniel Lezcano:
> On 10/25/2015 04:40 PM, Lucas Stach wrote:
> > Allow the timer core to change the smp affinity of the broadcast
> > timer
> > irq by setting CLOCK_EVT_FEAT_DYNIRQ flag.
> > 
> > This reduces interrupt pressure and wakeups on CPU0 as well as
> > vastly
> > reducing the number of timer broadcast IPIs.
> 
> Did you test this patch on a tegra2 ?
> 
Yes, I haven't spotted anything bad, but don't know if I should look
out for specific oddities?

Regards,
Lucas

Re: [PATCH] clocksource/drivers/tegra: allow timer irq affinity change

[Daniel Lezcano]

On 10/27/2015 09:22 PM, Lucas Stach wrote:
> Am Dienstag, den 27.10.2015, 11:14 +0100 schrieb Daniel Lezcano:
>> On 10/25/2015 04:40 PM, Lucas Stach wrote:
>>> Allow the timer core to change the smp affinity of the broadcast
>>> timer
>>> irq by setting CLOCK_EVT_FEAT_DYNIRQ flag.
>>>
>>> This reduces interrupt pressure and wakeups on CPU0 as well as
>>> vastly
>>> reducing the number of timer broadcast IPIs.
>>
>> Did you test this patch on a tegra2 ?
>>
> Yes, I haven't spotted anything bad, but don't know if I should look
> out for specific oddities?

I was wondering if you tested it because the changelog was the same than 
the similar change you did previously so I wanted to know if you assumed 
the behavior or if you tested it.

So, no problem.

Thanks !

   -- Daniel


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