At Wed, 21 Jan 2004 15:24:22 -0800,
Andrew Morton wrote:
>
>
> Takashi, it would be really, really useful if we could modify the ALSA
> drivers to identify at interrupt time when an underrun has occurred and to
> drop a stack dump at that point. Would that be possible? Something like:
>
> foo_interrupt()
> {
> ...
> if (there is no audio left to play) {
> if (sysctl_debug_audio_underruns) {
> printk("audio underrun!\n");
> dump_stack();
> }
> }
> ...
> }
>
> The backtrace will tell us what the kernel was doing when it should have
> been context switching instead. People can set the sysctl and send angry
> emails to kernel developers.
>
> Is this possible?
sure, we have already the underrun/overrun detection in the ALSA
common PCM layer (sound/core/pcm_lib.c: snd_pcm_update_hw_ptr_post).
just adding the code like above should work.
Takashi
