On Tue, 20 Nov 2007, Takashi Iwai wrote:
> changeset: 2352:39d34d6a4587
> tag: tip
> user: tiwai
> date: Tue Nov 20 15:29:10 2007 +0100
> files: src/pcm/pcm.c
> description:
> pcm - Limit the avail_min minimum size
>
> Fix avail_min if it's less than period_size. The too small avail_min
> is simply useless and the cause of CPU hog with rate plugin.
>
>
> diff -r b1d1733e52f8 -r 39d34d6a4587 src/pcm/pcm.c
> --- a/src/pcm/pcm.c Mon Nov 19 08:07:19 2007 +0100
> +++ b/src/pcm/pcm.c Tue Nov 20 15:29:10 2007 +0100
> @@ -5577,6 +5577,12 @@ int snd_pcm_sw_params_set_avail_min(snd_
> #endif
> {
> assert(pcm && params);
> + /* Fix avail_min if it's below period size. The period_size
> + * defines the minimal wake-up timing accuracy, so it doesn't
> + * make sense to set below that.
> + */
> + if (val < pcm->period_size)
> + val = pcm->period_size;
> params->avail_min = val;
> return 0;
> }
I think that this patch is wrong. We may use system timers to increase
(fine-tune) "interrupt" latencies for pcm streams - see tick time in
driver and library.
Jaroslav
-----
Jaroslav Kysela <perex@xxxxxxxx>
Linux Kernel Sound Maintainer
ALSA Project
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