Red Hat Bugzilla – Bug 253445
Leaving sound device opened is causing lots of wakeups
Last modified: 2009-01-08 23:51:13 EST
Description of problem:
Current Rawhide is causing about 60 wake ups per second when previously it was
causing an excellent 20 wps on the Desktop. The guilty according to powertop is
the interrupt CMI8738-MC6 (46 wps) even when idle and I am not playing any
sound. Even if I start to play some video the CMI thing keeps waking up the CPU
and the same rate so it is doing something unnecessarily.
As show in comment #6 from the wakeup bug report:
Rawhide from August 13 didn't have this problem and the wake ups were very low.
According to lspci my audio card is:
00:05.0 Multimedia audio controller: C-Media Electronics Inc CM8738 (rev 10)
and the related kernel modules are:
[root@localhost ~]# lsmod | grep -i cm
snd_cmipci 32737 5
gameport 15449 1 snd_cmipci
snd_pcm_oss 38625 0
snd_mixer_oss 16969 1 snd_pcm_oss
rtc_cmos 10977 0
snd_pcm 65389 4 snd_cmipci,snd_pcm_oss
snd_page_alloc 11209 1 snd_pcm
snd_opl3_lib 11865 1 snd_cmipci
snd_timer 20957 5 snd_seq,snd_pcm,snd_opl3_lib
snd_mpu401_uart 10585 1 snd_cmipci
snd 45189 18snd_cmipci,snd_seq_oss,snd_seq,snd_pcm_oss,
My system is an AMD Athlon XP 2000+ using kernel 2.6.23-0.115.rc3.git1.fc8
If you need more info just yelp.
Mmmm... doing extra investigation I realized that this is caused by esd now
being enable by default and not by a kernel module regression.
When I disable it in gnome-sound-properties, wake ups go down to normal.
This is a problem with the sound system (ALSA). Whenever the device is opened,
the hardware will generate interrupts. It's a kernel problem that's unlikely to
be fixed. We'll get the fix for free when we switch to using PulseAudio by default.
*** Bug 252352 has been marked as a duplicate of this bug. ***
note that there are two aspects to this bug:
1) the wakeups caused by "device open but no sound"
2) keeping/having the device open will prevent power saving from kicking in.
I'll agree that 1) is an alsa core issue that alsa should be fixing ideally; but
2) is an esd issue; powersaving (turning off power to the codec and sound chip)
kicks in on device closing, and that's the only thing that is right to do, since
only "nobody has the device open" can qualify as criterium for this.
A couple of things.
First, esound doesn't like not being started from the session. See the default
# autospawning is not recommended, since it can't really be done
# right. If you want your login session to be using a sound daemon,
# you should start it from the session controller, not some random
# app inside.
Secondly, esound isn't the default in F8 anymore (it's been replaced by
PulseAudio in F8, along with esound-compat libraries).
Finally, Lennart mentioned that Takashi is working on using high-resolution
times for ALSA's ring buffer management, which means that we'd be able to not
use interrupts on the hardware.
So this bug needs to go to PA, or the kernel. As the fixes should happen in the
kernel, pushing there.
*** Bug 251534 has been marked as a duplicate of this bug. ***
Retitling to be more accurate.
pushing this to the kernel does not and will not fix the 2nd issue (preventing
sound hardware from going to sleep), but I suppose we need to create a second
bug for that.
Based on the date this bug was created, it appears to have been reported
during the development of Fedora 8. In order to refocus our efforts as
a project we are changing the version of this bug to '8'.
If this bug still exists in rawhide, please change the version back to
(If you're unable to change the bug's version, add a comment to the bug
and someone will change it for you.)
Thanks for your help and we apologize for the interruption.
The process we're following is outlined here:
We will be following the process here:
http://fedoraproject.org/wiki/BugZappers/HouseKeeping to ensure this
doesn't happen again.
This message is a reminder that Fedora 8 is nearing its end of life.
Approximately 30 (thirty) days from now Fedora will stop maintaining
and issuing updates for Fedora 8. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
this bug will be closed as WONTFIX if it remains open with a Fedora
'version' of '8'.
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to a later Fedora version prior to Fedora 8's end of life.
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Although we aim to fix as many bugs as possible during every release's
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The process we are following is described here:
Fedora 8 changed to end-of-life (EOL) status on 2009-01-07. Fedora 8 is
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