Re: High CPU audio drops?
Re: High CPU audio drops?
- Subject: Re: High CPU audio drops?
- From: Kyle Sluder <email@hidden>
- Date: Thu, 31 Dec 2015 11:32:01 -0600
On Wed, Dec 30, 2015, at 10:33 AM, Michael McNeela wrote:
> The audio just glitched & dropped to silence a couple of days after the
> app
> was launched 'by hand' rather than via launchd, so I guess that rules out
> the thread priorities… *sigh* ;p
Well, you could still be in a priority inversion situation, where the
high-priority audio rendering thread is being starved by a
lower-priority thread that is failing to fill up a ring buffer with
samples. (For example, a decoder running on a background thread.)
How are you actually playing data? Are you generating sample data
yourself (even if it's something as simple as mixing)? What does your
threading model look like?
--Kyle Sluder
>
> (The app runs the music in a bar/nightclub, hence why the Mac was running
> for a couple of days)
>
> *Michael*
> 07595247282
>
> On 26 Dec 2015, at 23:10, Michael McNeela <email@hidden> wrote:
>
> OK, what about the audio realtime thread (during playback). It should be
> running at pri 97 -- is this true while the glitches are happening?
>
>
> It’s indeed at 97 for both type of launch, but …the glitches tend to take
> a
> few hours/days of running to present themselves (!), so I’ll just try
> ditching launchd for a few days & see if the random glitching disappears
> (that’s how that attached ’things I’ve tried' matrix came to be :p)
>
> (Thanks for the push in the potentially-right direction by the way!)
>
> *Michael*
> +447595247282
>
> On 26 Dec 2015, at 22:52, Doug Wyatt <email@hidden> wrote:
>
> OK, what about the audio realtime thread (during playback). It should be
> running at pri 97 -- is this true while the glitches are happening?
>
> Doug
>
> # sent from my iPhone
>
> On Dec 26, 2015, at 14:40, Michael McNeela <email@hidden> wrote:
>
> Hey Doug
>
> Your matrix makes me wonder: are you trying to play from a launchd
> daemon?
>
>
> Yep; a launchd LaunchAgents daemon (i.e. not running as root)
>
> Try taking an Instruments trace that captures thread scheduling activity.
> It sounds like the daemon is in a throttled state, which would show in a
> kernel or Instruments trace as having its threads running at a very low
> priority.
>
>
> A short ~5 second trace seems to show the *main thread* via launchd
> consistently at priority 31, vs the main thread via ‘double-click to
> open’
> at priority 46-47. (All other threads seem to have the same priorities
> regardless of how the app’s launched though)
>
> *Michael*
> +447595247282
>
> On 26 Dec 2015, at 18:34, Doug Wyatt <email@hidden> wrote:
>
> Hi Michael,
>
> Your matrix makes me wonder: are you trying to play from a launchd
> daemon?
>
> Try taking an Instruments trace that captures thread scheduling activity.
> It sounds like the daemon is in a throttled state, which would show in a
> kernel or Instruments trace as having its threads running at a very low
> priority.
>
> Doug
>
>
>
> On Dec 26, 2015, at 10:11 , Michael McNeela <email@hidden> wrote:
>
> Should you be curious, here’s what I’ve tried narrowing down so far;
>
> <Screen Shot 2015-12-26 at 18.06.39 copy.jpeg>
>
> *Michael*
> 07595247282
>
> On 26 Dec 2015, at 16:55, Michael McNeela <email@hidden> wrote:
>
> On 26 Dec 2015, at 16:48, Cyril Blanc <email@hidden>
> wrote:
>
> Where are your video files ?
>
>
> On the internal SSD
>
> What Mac do you use ?
>
>
> A late 2014 Mac mini (Macmini7,1), factory-configured to 2.6 GHz i5, 8GB
> RAM, 256GB SSD. The issue presents itself on three Macs of the same
> hardware configuration (bought & configured at roughly the same time),
> across 10.10.3, 10.10.5 and 10.11. I’m puzzled.
>
> *Michael*
> 07595247282
>
> On 26 Dec 2015, at 16:50, Michael McNeela <email@hidden> wrote:
>
> Thanks for the input everybody. I should clarify that I’m simply playing
> regular ol’ video files using Cocoa’s AVPlayer; nothing spectacular, and
> the video playback continues unaffected as the audio stutters and drops.
> It’s incredibly odd.
>
> Oh, and audio is being outputted through the Mac’s headphone port; not
> external audio interface via USB/FireWire, etc.
>
> I’ve stopped SSH attempts bumping the CPU, just in case they were
> related,
> but the issue persists, so now I’m at a loss.
>
> *Michael*
> 07595247282
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