Re: [Alsa-user] Pb with simultaneous SATA and ALSA I/O

From: Dominique Dumont
Date: Wed Oct 04 2006 - 06:45:56 EST


Lee Revell <rlrevell@xxxxxxxxxxx> writes:

> It might not be interrupt related, it could be DMA starvation. This has
> been observed with some SATA controllers while testing the -rt patches.
> The symptom is that the latency traces show the machine going in "slow
> motion".
>
> Dominique: try the -rt kernel, enable latency tracing and post the
> output.

Done. I've tried with 2.6.18-rt5. CONFIG_LATENCY_TRACE is enabled.

Here are the results (still with running "ac3dec -C " and "md5sum *"
on a SATA drive):
- I get no more ALSA xrun.
- /proc/latency_trace is empty
- dolby digital output is still considerably chopped.

Note that the dolby digital output works fine when:
- No I/O is done
- heavy I/O on pata HDD (md5sum *)
- heavy I/O on DVD reader (md5sum *)

Did I miss something with the latency_trace ?

Cheers
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