[LAD] Realtime threads and security

[Olivier Guilyardi]

Hi,

On 02/17/2011 10:53 PM, Robin Gareus wrote:

> /proc/sys/kernel/sched_rt_runtime_us
> /proc/sys/kernel/sched_rt_period_us
> 
> <kernel-source>/Documentation/scheduler/sched-rt-group.txt

There's something which confuses me. But I'm not sure how this realtime period
settings relate to the audio I/O period.

On Android, the closest that one can get to hardware in a more or less portable
way is libaudio [1]. It's Android's audio HAL. This API exposes blocking read()
and write() calls, with fixed buffer sizes (input and output buffer sizes
generally do not match, but that's another problem).

So, this may be a silly/newbie question, but can one access this blocking API
from a realtime thread? What will happen when it blocks? How does the read/write
period relate to sched_rt_period_us?

[1] http://source.android.com/porting/audio.html

--
  Olivier