linux-kernel - Re: Linux-next Alsa hda_intel events/0 high CPU usage, bisected

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Date:	Tue, 10 Jun 2008 05:20:49 -0700 (PDT)
From:	Benjamin Kidwell <benjkidwell@...oo.com>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Linux-next Alsa hda_intel events/0 high CPU usage, bisected

> --- Takashi Iwai <> wrote:
>Try to run
>
>	# echo 32 > /sys/modules/snd_hda_intel/parameters/bdl_pos_adj
>and test again.

Thanks, I think that value must be just about perfect! Tested as follows:

(kill gdm)
#modprobe -r snd_hda_intel
#modprobe snd_hda_intel
#echo 32 > /sys/module/snd_hda_intel/bdl_pos_adj
(restart gdm, start playing sound)

That caused events/0 CPU% to return to almost nothing and the XXX hda delay
output did not trigger. I assume this means the latency has disappeared. For
comparison, I repeated the above processand returned bdl_pos_adj to 1, and the
delay printks reappeared and events/0 started showing significant cpu usage
again. Another reset of the driver and I reset bdl_pos_adj to 32 -- no delay
printks, almost no events/0 activity apparent.

So setting bdl_pos_adj to 32 with all new patches applied makes everything
perfect so far as I can tell. Thanks for the fix-ups for my buggy hardware,
and for reminding me to use reply and Cc: correctly. Let me know if there's
anything else I should test.
Ben

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