Re: [Alsa-devel] Re: irq handler top half timestamps

[Ingo Molnar <mingo@elte.hu>]

* Florian Schmidt <mista.tapas@gmx.net> wrote:

> On Sat, 11 Dec 2004 03:22:14 +0100
> Florian Schmidt <mista.tapas@gmx.net> wrote:
> 
> > Oh, i almost forgot: Ingo has already posted a patch adding this to the
> > threaded irq handlers in recent RP kernels. ALSA could access it. But
> > making ALSA depend on a kernel feature of an experimental kernel might
> > be unwise (uneducated guess). 
> > 
> > Also this leaves the question of using a different timer source for the
> > timestamps in the case that TSC is unreliable open.
> > 
> > Is it sensible to require users of jackd to not use cpu freq scaling
> > during operation? If so, we could just settle on using the TSC.
> > 
> > Flo
> > 
> 
> is
> 
> snd_pcm_get_trigger_tstamp()
> 
> the api call to get the timestamp of the irq handler?
> 
> flo

in case you want to add it to ALSA within the -RT patchset, -RT now has
a generic function:

 extern cycles_t irq_timestamp(unsigned int irq);

the timestamps do get generated for every irq.

(but ... the usual disclaimer: this is just a playground thing, so
there's no guarantee of upstream merging.)

	Ingo


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