Re: [PATCH 09/13] powerpc/64s: cpuidle set polling before enabling irqs

[Michael Ellerman]

Nicholas Piggin  writes:

> On Wed, 14 Jun 2017 21:40:52 +1000
> Michael Ellerman  wrote:
>
>> Nicholas Piggin  writes:
>> 
>> > local_irq_enable can cause interrupts to be taken which could
>> > take significant amount of processing time. The idle process
>> > should set its polling flag before this, so another process that
>> > wakes it during this time will not have to send an IPI.
>> >
>> > Expand the TIF_POLLING_NRFLAG coverage to as large as possible.
>> >
>> > Reviewed-by: Gautham R. Shenoy 
>> > Signed-off-by: Nicholas Piggin 
>> > ---
>> >  drivers/cpuidle/cpuidle-powernv.c | 4 +++-
>> >  drivers/cpuidle/cpuidle-pseries.c | 3 ++-
>> >  2 files changed, 5 insertions(+), 2 deletions(-)  
>> 
>> I don't think the cpuidle folks are really interested in these changes,
>> but we should Cc them to be polite.
>> 
>> Can you resend patches 9, 10, 11 with a subject like:
>> 
>>   "cpuidle: powernv: Set polling ..."
>> 
>> And Cc the cpuidle folks:
>> 
>> $ ./scripts/get_maintainer.pl -f drivers/cpuidle
>> r...@rjwysocki.net
>> daniel.lezc...@linaro.org
>> linux...@vger.kernel.org
>> linux-ker...@vger.kernel.org
>
> Yeah I can do that. I'll send them as thier own series. They don't
> depend on any of the patches in this series, so I should have done
> that in the first place.

Great thanks.

cheers

Re: [PATCH 09/13] powerpc/64s: cpuidle set polling before enabling irqs

[Nicholas Piggin]

On Wed, 14 Jun 2017 21:40:52 +1000
Michael Ellerman  wrote:

> Nicholas Piggin  writes:
> 
> > local_irq_enable can cause interrupts to be taken which could
> > take significant amount of processing time. The idle process
> > should set its polling flag before this, so another process that
> > wakes it during this time will not have to send an IPI.
> >
> > Expand the TIF_POLLING_NRFLAG coverage to as large as possible.
> >
> > Reviewed-by: Gautham R. Shenoy 
> > Signed-off-by: Nicholas Piggin 
> > ---
> >  drivers/cpuidle/cpuidle-powernv.c | 4 +++-
> >  drivers/cpuidle/cpuidle-pseries.c | 3 ++-
> >  2 files changed, 5 insertions(+), 2 deletions(-)  
> 
> I don't think the cpuidle folks are really interested in these changes,
> but we should Cc them to be polite.
> 
> Can you resend patches 9, 10, 11 with a subject like:
> 
>   "cpuidle: powernv: Set polling ..."
> 
> And Cc the cpuidle folks:
> 
> $ ./scripts/get_maintainer.pl -f drivers/cpuidle
> r...@rjwysocki.net
> daniel.lezc...@linaro.org
> linux...@vger.kernel.org
> linux-ker...@vger.kernel.org

Yeah I can do that. I'll send them as thier own series. They don't
depend on any of the patches in this series, so I should have done
that in the first place.

Thanks,
Nick

Re: [PATCH 09/13] powerpc/64s: cpuidle set polling before enabling irqs

[Michael Ellerman]

Nicholas Piggin  writes:

> local_irq_enable can cause interrupts to be taken which could
> take significant amount of processing time. The idle process
> should set its polling flag before this, so another process that
> wakes it during this time will not have to send an IPI.
>
> Expand the TIF_POLLING_NRFLAG coverage to as large as possible.
>
> Reviewed-by: Gautham R. Shenoy 
> Signed-off-by: Nicholas Piggin 
> ---
>  drivers/cpuidle/cpuidle-powernv.c | 4 +++-
>  drivers/cpuidle/cpuidle-pseries.c | 3 ++-
>  2 files changed, 5 insertions(+), 2 deletions(-)

I don't think the cpuidle folks are really interested in these changes,
but we should Cc them to be polite.

Can you resend patches 9, 10, 11 with a subject like:

  "cpuidle: powernv: Set polling ..."

And Cc the cpuidle folks:

$ ./scripts/get_maintainer.pl -f drivers/cpuidle
r...@rjwysocki.net
daniel.lezc...@linaro.org
linux...@vger.kernel.org
linux-ker...@vger.kernel.org

cheers

[PATCH 09/13] powerpc/64s: cpuidle set polling before enabling irqs

[Nicholas Piggin]

local_irq_enable can cause interrupts to be taken which could
take significant amount of processing time. The idle process
should set its polling flag before this, so another process that
wakes it during this time will not have to send an IPI.

Expand the TIF_POLLING_NRFLAG coverage to as large as possible.

Reviewed-by: Gautham R. Shenoy 
Signed-off-by: Nicholas Piggin 
---
 drivers/cpuidle/cpuidle-powernv.c | 4 +++-
 drivers/cpuidle/cpuidle-pseries.c | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c 
b/drivers/cpuidle/cpuidle-powernv.c
index 79152676f62b..50b3c2e0306f 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -51,9 +51,10 @@ static int snooze_loop(struct cpuidle_device *dev,
 {
u64 snooze_exit_time;
 
-   local_irq_enable();
set_thread_flag(TIF_POLLING_NRFLAG);
 
+   local_irq_enable();
+
snooze_exit_time = get_tb() + snooze_timeout;
ppc64_runlatch_off();
HMT_very_low();
@@ -66,6 +67,7 @@ static int snooze_loop(struct cpuidle_device *dev,
ppc64_runlatch_on();
clear_thread_flag(TIF_POLLING_NRFLAG);
smp_mb();
+
return index;
 }
 
diff --git a/drivers/cpuidle/cpuidle-pseries.c 
b/drivers/cpuidle/cpuidle-pseries.c
index 166ccd711ec9..7b12bb2ea70f 100644
--- a/drivers/cpuidle/cpuidle-pseries.c
+++ b/drivers/cpuidle/cpuidle-pseries.c
@@ -62,9 +62,10 @@ static int snooze_loop(struct cpuidle_device *dev,
unsigned long in_purr;
u64 snooze_exit_time;
 
+   set_thread_flag(TIF_POLLING_NRFLAG);
+
idle_loop_prolog(_purr);
local_irq_enable();
-   set_thread_flag(TIF_POLLING_NRFLAG);
snooze_exit_time = get_tb() + snooze_timeout;
 
while (!need_resched()) {
-- 
2.11.0