Extreme CPU usage on linux

[naught101]

Currently, I have Mixxx open, with tracks loaded, but not playing anything. The CPU usage is sitting at over 200%:

top - 13:54:10 up 1:50, 6 users, load average: 6.86, 5.07, 4.25
Tasks: 332 total, 3 running, 328 sleeping, 0 stopped, 1 zombie
%Cpu(s): 44.9 us, 5.1 sy, 0.0 ni, 42.6 id, 7.3 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 8087684 total, 7768972 used, 318712 free, 304856 buffers
KiB Swap: 15359996 total, 0 used, 15359996 free. 2473232 cached Mem

  PID PPID UID USER RUSER TTY NI TIME+ %CPU %MEM S COMMAND
13488 5644 1000 naught1+ naught1+ ? 0 206:56.76 226.8 9.4 S mixxx
24482 24356 1000 naught1+ naught1+ ? 0 2:38.69 106.8 2.4 S BitwigStudioEng
24356 5644 1000 naught1+ naught1+ ? 0 0:57.85 35.8 5.0 S bitwig-studio
13849 5439 1000 naught1+ naught1+ ? -11 3:02.57 11.3 0.2 S pulseaudio

When I have something playing, it sits well over 300%.

Computer specs: http://www.engadget.com/products/samsung/series-7/chronos/specs/

$ uname -a
Linux naught101-chronos 3.13.0-44-lowlatency #73-Ubuntu SMP PREEMPT Tue Dec 16 00:48:57 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
Kubuntu 14.04.1 LTS

Mixxx was installed from source using `scons prefix=/usr/local faad=1 -j2 install` (so that I could have m4a/aac support)

This seems pretty intensive for something that's just playing music. Is this normal? If it's as extreme as it seems, let me know if I can provide any more information.

[Owen Williams (ywwg)]

Still happening? I don't see this, even with very small buffer sizes. Also what's your CPU? Also we've had bad experience with the "lowlatency" kernels, the default kernel works better, even at low latencies :)

[naught101 (naught101)]

Yep, still happening. Intel Core i7. I will try with the standard kernel.

[Owen Williams (ywwg)]

hm I also see that pulseaudio and bitwig are running. What sound settings are you using?

[naught101 (naught101)]

I was using mixxx via ALSA/Pulse, but the same performance problem occurs when I'm using the soundcard (hw:0,0) directly. And the CPU usage is high regardless of whether Bitwig is running - that was just there for comparison.

[Owen Williams (ywwg)]

Can you run mixxx with the --developer flag and then post your mixxx.log?

[naught101 (naught101)]

Attached. So, I just noticed that if I just start mixxx, CPU usage sits at ~40%. If I load a track in deck 1, it jumps to ~180%. If I load another track into deck2, it jumps to ~270%. This is without playing anything. If I eject the tracks from the decks, the CPU usage drops back down to ~50%. Perhaps this is related to waveform rendering?

[naught101 (naught101)]

Yep. If I set waveforms -> summary to "empty", then load tracks, Mixxx stays well below ~10% CPU. It's high when I use filtered (GL) or filtered (GLSL).

[Owen Williams (ywwg)]

yeah almost certainly waveforms. What's your video card / driver combo? Is there any GL-based waveform that doesn't result in a spike? How are the 2d waveforms?

[Owen Williams (ywwg)]

What skin are you using? I see a warning that "play_sync" doesn't exist, and this object does not appear in the current trunk builds.

[naught101 (naught101)]

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc.
[AMD/ATI] Seymour [Radeon HD 6400M/7400M Series] [1002:6760] (prog-if 00
[VGA controller])
         Subsystem: Samsung Electronics Co Ltd Radeon HD 6490M [144d:c0b3]
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop-
ParErr- Stepping- SERR- FastB2B- DisINTx+
         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx-
         Latency: 0, Cache Line Size: 64 bytes
         Interrupt: pin A routed to IRQ 52
         Region 0: Memory at a0000000 (64-bit, prefetchable) [size=256M]
         Region 2: Memory at c0700000 (64-bit, non-prefetchable) [size=128K]
         Region 4: I/O ports at 3000 [size=256]
         Expansion ROM at c0720000 [disabled] [size=128K]
         Capabilities: <access denied>
         Kernel driver in use: radeon

All of the GL shaders cause increased CPU usage, to varying degrees
(e.g. at least ~160%).

Using LateNight, a build from git from about a month ago. I can update it.

On 03/02/2015 02:03 PM, Owen Williams wrote:
> yeah almost certainly waveforms. What's your video card / driver combo?
> Is there any GL-based waveform that doesn't result in a spike? How are
> the 2d waveforms?

> What skin are you using? I see a warning that "play_sync" doesn't
> exist, and this object does not appear in the current trunk builds.
>

[Owen Williams (ywwg)]

do you know which driver are you using, free or proprietary?

[naught101 (naught101)]

The open source radeon driver.

[RJ Skerry-Ryan (rryan)]

naught101 -- does this still happen with Mixxx 2.1 or 2.2 beta?

[Launchpad Janitor (janitor)]

[Expired for Mixxx because there has been no activity for 60 days.]

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/7833