Macbook Pro Retina 15-inch stuttering sound when high CPU usage

Question

I have Boot Camp on my rMBP 15-inch, running Windows 8.1. I usually have Spotify running in the background when I work. Recently, I notice whenever my CPU usage is high (>80%), the music is stuttering and distorted. Not just Spotify but any sound or music player got affected.

I have Boot Camp 5.1 installed for almost a year and never experience this problem before. Recently I upgraded to Boot Camp 6 (with Windows 8.1). I suspect it must be some soundcard drivers problem, but even after reinstalling the Boot Camp Driver, the problem remain.

Is there anything I can do to diagnose the root cause of this behavior ?

Answer 1

I used the following xperf command to get an overview of the DPC activity on your system:

"C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit\xperf.exe" -I DIOMBPWS03-07-2016.23-45-01.etl -a dpcisr > dpc.txt

In the DPC.txt I see you have some large spikes (over 1024µs execution time), that cause such audio glitches:

Total = 7394 for module USBXHCI.SYS
Elapsed Time, >     2048 usecs AND <=     4096 usecs,      0, or   0.00%
Elapsed Time, >     4096 usecs AND <=     8192 usecs,      1, or   0.01%
Elapsed Time, >     8192 usecs AND <=    16384 usecs,      2, or   0.03%
Elapsed Time, >    16384 usecs AND <=    32768 usecs,      0, or   0.00%
Elapsed Time, >    32768 usecs AND <=    65536 usecs,      1, or   0.01%
Total,                                                  7394

Total = 10028 for module afd.sys
Elapsed Time, >     1024 usecs AND <=     2048 usecs,      0, or   0.00%
Elapsed Time, >     2048 usecs AND <=     4096 usecs,      0, or   0.00%
Elapsed Time, >     4096 usecs AND <=     8192 usecs,      4, or   0.04%
Total,                                                 10028

Total = 7092 for module ndis.sys
Elapsed Time, >      512 usecs AND <=     1024 usecs,      1, or   0.01%
Elapsed Time, >     1024 usecs AND <=     2048 usecs,      0, or   0.00%
Elapsed Time, >     2048 usecs AND <=     4096 usecs,      1, or   0.01%
Elapsed Time, >     4096 usecs AND <=     8192 usecs,      1, or   0.01%
Total,                                                  7092

Total = 28123 for module ntoskrnl.exe
Elapsed Time, >     1024 usecs AND <=     2048 usecs,      0, or   0.00%
Elapsed Time, >     2048 usecs AND <=     4096 usecs,      1, or   0.00%
Elapsed Time, >     4096 usecs AND <=     8192 usecs,      6, or   0.02%
Total,                                                 28123


Total = 36449 for module storport.sys
Elapsed Time, >     1024 usecs AND <=     2048 usecs,      0, or   0.00%
Elapsed Time, >     2048 usecs AND <=     4096 usecs,      0, or   0.00%
Elapsed Time, >     4096 usecs AND <=     8192 usecs,      4, or   0.01%
Total,                                                 36449

Total = 29689 for module nvlddmkm.sys
Elapsed Time, >     1024 usecs AND <=     2048 usecs,      1, or   0.00%
Elapsed Time, >     2048 usecs AND <=     4096 usecs,      3, or   0.01%
Elapsed Time, >     4096 usecs AND <=     8192 usecs,      1, or   0.00%
Total,                                                 29689

The largest issues come from the USB 3.0 driver (USBXHCI.SYS) of Windows 8.1 which has a spike of 0,032768s, which is terrible.

I looked at the callstack and see that the USB driver does some IO transfer (USBXHCI.SYS!UsbDevice_TransferEventHandler). So disable some of the USB devices that you use until you find the device that causes the usage.