Can not play audio with screen off

Can not play audio with screen off

[Pavel Machek]

Hi!

I'm playing some more with N900, this time I'd like to use it as a
alarm clock...

And now I realized I can not, because system performance is so
horrible with screen off that mpg123 + pulseaudio skips horribly. This
is without tweaking serial parameters, so CPU is definitely not going
into the idle/off modes.

Loading CPU fixes the issue (I used cat /dev/zero > /dev/null).

Hmm. And it seems to work better if I ssh in and launch mpg123
remotely. Weird.

Kernel 4.5-rc0. Will try on different ones.

Any ideas? Is there interface to tell kernel that better performance
is needed for a while?

Thanks,

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: Can not play audio with screen off

[Nishanth Menon]

On 05/15/2016 02:31 PM, Pavel Machek wrote:
> Hi!
> 
> I'm playing some more with N900, this time I'd like to use it as a
> alarm clock...
> 
> And now I realized I can not, because system performance is so
> horrible with screen off that mpg123 + pulseaudio skips horribly. This
> is without tweaking serial parameters, so CPU is definitely not going
> into the idle/off modes.
> 
> Loading CPU fixes the issue (I used cat /dev/zero > /dev/null).
> 
> Hmm. And it seems to work better if I ssh in and launch mpg123
> remotely. Weird.
> 
> Kernel 4.5-rc0. Will try on different ones.
> 
> Any ideas? Is there interface to tell kernel that better performance
> is needed for a while?
> 

pm_qos cpu_dma_latency? Drivers will have to be properly instrumented
with appropriate latency values -> this will control the depth in C
states that the system will attempt. NOTE: it is a dual edged sword,
bad configurations can result in none of the C-states being entered.


-- 
Regards,
Nishanth Menon

Re: Can not play audio with screen off

[Pavel Machek]

Hi!

> > I'm playing some more with N900, this time I'd like to use it as a
> > alarm clock...
> > 
> > And now I realized I can not, because system performance is so
> > horrible with screen off that mpg123 + pulseaudio skips horribly. This
> > is without tweaking serial parameters, so CPU is definitely not going
> > into the idle/off modes.
> > 
> > Loading CPU fixes the issue (I used cat /dev/zero > /dev/null).
> > 
> > Hmm. And it seems to work better if I ssh in and launch mpg123
> > remotely. Weird.
> > 
> > Kernel 4.5-rc0. Will try on different ones.
> > 
> > Any ideas? Is there interface to tell kernel that better performance
> > is needed for a while?

> pm_qos cpu_dma_latency? Drivers will have to be properly instrumented
> with appropriate latency values -> this will control the depth in C
> states that the system will attempt. NOTE: it is a dual edged sword,
> bad configurations can result in none of the C-states being entered.

Ok, so far it looks like artefact of -rc0 kernel. Lets see if it
reappers...

Thanks,
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: Can not play audio with screen off

[Pavel Machek]

Hi!

> > > I'm playing some more with N900, this time I'd like to use it as a
> > > alarm clock...
> > > 
> > > And now I realized I can not, because system performance is so
> > > horrible with screen off that mpg123 + pulseaudio skips horribly. This
> > > is without tweaking serial parameters, so CPU is definitely not going
> > > into the idle/off modes.
> > > 
> > > Loading CPU fixes the issue (I used cat /dev/zero > /dev/null).
> > > 
> > > Hmm. And it seems to work better if I ssh in and launch mpg123
> > > remotely. Weird.
> > > 
> > > Kernel 4.5-rc0. Will try on different ones.
> > > 
> > > Any ideas? Is there interface to tell kernel that better performance
> > > is needed for a while?
> 
> > pm_qos cpu_dma_latency? Drivers will have to be properly instrumented
> > with appropriate latency values -> this will control the depth in C
> > states that the system will attempt. NOTE: it is a dual edged sword,
> > bad configurations can result in none of the C-states being entered.
> 
> Ok, so far it looks like artefact of -rc0 kernel. Lets see if it
> reappers...

Hmm. So it happens in vanilla 4.4, too... let me see if it happens in
v4.6.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html