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geekmaster · 07-11-2012, 03:59 AM

I just repeated the above experiment on my K5, using top instead of htop. It reported that gmplay used 15% CPU (as expected because the K5 sleeps while the K3 is inside the eink update call). The tones program immediately aborts with the following errors:

Code:

ALSA lib pcm_hw.c:1429:(_snd_pcm_hw_open) Unknown field hint
Playback open error: Invalid argument

It appears that the K3 eink update calls are the culprit, consuming all that CPU time during system calls (which was also reported by hawhill some time ago). There must be some nasty wait loops or spinlocks, as mentioned before.

Those long busy eink updates on a K3 may interfere with sound, unless the sound is interrupt driven.

At least sound and video should work well together on a K4 or newer (after porting the sound code to the newer kindles).

FYI, the K3 spends about 140 msec full frame eink update calls, so sound buffering should be at least that long, and preferably synchronized to the framerate. On a DX and DXG, the 600x800 (not fullscreen) eink updates take about 650 msec to compete.

07-11-2012, 03:59 AM	#91
geekmaster Carpe diem, c'est la vie. Posts: 6,433 Karma: 10773670 Join Date: Nov 2011 Location: Multiverse 6627A Device: K1 to PW3	I just repeated the above experiment on my K5, using top instead of htop. It reported that gmplay used 15% CPU (as expected because the K5 sleeps while the K3 is inside the eink update call). The tones program immediately aborts with the following errors: Code: ALSA lib pcm_hw.c:1429:(_snd_pcm_hw_open) Unknown field hint Playback open error: Invalid argument It appears that the K3 eink update calls are the culprit, consuming all that CPU time during system calls (which was also reported by hawhill some time ago). There must be some nasty wait loops or spinlocks, as mentioned before. Those long busy eink updates on a K3 may interfere with sound, unless the sound is interrupt driven. At least sound and video should work well together on a K4 or newer (after porting the sound code to the newer kindles). FYI, the K3 spends about 140 msec full frame eink update calls, so sound buffering should be at least that long, and preferably synchronized to the framerate. On a DX and DXG, the 600x800 (not fullscreen) eink updates take about 650 msec to compete. Last edited by geekmaster; 07-11-2012 at 04:20 AM.