DPC latency issue (crackling audio) dxgkrnl.sys - Windows 7 x86 SP1

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Lasty

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Feb 8, 2014
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I followed the tutorial on pin pointing DCP latency issue using latencymon. My highest executions was dxgkrnl.sys so now im wondering what the next step would be towards fixing that.
 
Hi,

Could you please run Windows SDK setup and select to install "Windows Performance Toolkit"? Once it's installed run the following command from elevated (Run As Administrator) command prompt (if the command asks you to modify the registry, please do that, reboot your computer and re-run the command):

Code: 
xperf -on PROC_THREAD+LOADER+PROFILE+INTERRUPT+DPC+DRIVERS -stackwalk Profile -BufferSize 1024 -MinBuffers 256 -MaxBuffers 256 -MaxFile 256 -FileMode Circular

Now, play some audio until you experience the lag issues you mentioned. Once you do, run the following command to stop the logging:

Code: 
xperf -stop -d C:\CPU.etl

Compress C:\CPU.etl log file and attach it here.

Thanks.
 
that first code gave me xperf error -MaxBuffers does not expect 3 arguments

typing just xperf -on gives me xperf error NT kernel logger Access is denied
 
now its giving me xperf error NT kernel logger the process cannot access the file because it is being used by another process
 
Try rebooting the system and running the first command again. Make sure you copy the command properly, you are running command prompt as administrator adn there are no other tracing programs (e.g. LatencyMon, Process Monitor etc.) running on the system at the same time.
 
What OS are you running?

Have you checked for a BIOS update?

Are your video & audio drivers updated?

dxgkrnl.sys = Microsoft DirectX Graphics Kernel
 
Last edited:
Ok a couple things: I am running windows 7 32bit SP1.
now as far as i saw there were no updates for my vcard which is a pny geforce gt 630 but when i unplugged it and restarted and checked latencymon dxgkrnl.sys was no longer the top of the list NOW ntkrnlpa.exe is the highest with ndis.sys spiking high one time. The crackling isnt as bad though but still there and comp is still laggy. When i tried to run that command now without my video card hooked in i got the message NT kernel logger a device attached to the system is not functioning. So im gonna shutdown plud in my gpu and try it again
 
well after fighting with my computer to get my video card up and running again, the laggyness is worse and i still get the same message trying to run the xperf -on PROC_THREAD+LOADER+PROFILE+INTERRUPT+DPC+DRIVERS -stackwalk Profile -BufferSize 1024 -MinBuffers 256 -MaxBuffers 256 -MaxFile 256 -FileMode Circular "a device attached to the system is not functioning"
 
Lasty said:
well after fighting with my computer to get my video card up and running again, the laggyness is worse and i still get the same message trying to run the xperf -on PROC_THREAD+LOADER+PROFILE+INTERRUPT+DPC+DRIVERS -stackwalk Profile -BufferSize 1024 -MinBuffers 256 -MaxBuffers 256 -MaxFile 256 -FileMode Circular "a device attached to the system is not functioning"
Click to expand...

Could you please open elevated ("Run as administrator") command prompt, type verifier /querysettings and paste the results here?
 
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.


C:\Windows\system32>xperf -on PROC_THREAD+LOADER+PROFILE+INTERRUPT+DPC+DRIVERS -
stackwalk Profile -BufferSize 1024 -MinBuffers 256 -MaxBuffers 256 -MaxFile 256
-FileMode Circular
xperf: error: NT Kernel Logger: A device attached to the system is not functioni
ng. (0x1f).


C:\Windows\system32>verifier /querysettings
Special pool: Enabled
Pool tracking: Enabled
Force IRQL checking: Enabled
I/O verification: Disabled
Deadlock detection: Enabled
DMA checking: Disabled
Security checks: Enabled
Force pending I/O requests: Disabled
Low resources simulation: Disabled
IRP Logging: Disabled
Miscellaneous checks: Enabled


Verified drivers:


amdxata.sys
pxhelp20.sys
nvlddmkm.sys
nvbridge.kmd
sisgb6.sys
ndis.sys
smserial.sys
dump_dumpata.sys
dump_atapi.sys
dump_dumpfve.sys
atmfd.dll
secdrv.sys


C:\Windows\system32>
 
OK, the results shows exactly what I suspected :smile9:

XPERF is not running because you have Special pool: Enabled (I saw this case somewhere else long time ago). Moreover, I see that you have Driver Verifier enabled on your video card drivers (nvlddmkm.sys). Once enabled, Driver Verifier adds extra overhead for the system, making many operations more slow. What that means in this case, that there are chances that Driver Verifier is the cause of the DPC latencies you report.

Please run verifier /reset from administrative command prompt and reboot the system. After the reboot, run verifier /querysettings again to be sure all settings are disabled. Let us know if the DPC issues persists.
 
*The above is without my Video card connected*
I should add, since ive been using this video card (about 2 months) when i start up my computer right after the starting windows screen, my screen would always go blank for anywhere from 10-20 seconds up to a minute or so then go to the user login. So since ive started all this tinkering my video card has become unstable. It will hang up on the blank screen permenantly when loading up. If i boot into safe mode it works fine though so this prompted me to call nvidia they told me to update my bios which i did. A few times during this ive gotten a BSOD with nvlddmkm.sys being the cause. Basically video card works fine in safe mode, I have tried installing various drivers for it in safe mode but when i restart after to go into normal mode i get stuck on the blank screen after windows starting screen. Right now im just going without the video card and latencymon has ndis.sys the highest for toal execusions.
 
OK, let's clarify this:

  • If you still have cracking audio without your video card (that is, using integrated video card), please run XPERF. It should run fine after we disabled Driver Verifier
  • If the cracking audio issues occur only when you use your video card and you also get BSODs and various other issues (like blank screens you mentioned), then we shouldn't be troubleshooting this as a DPC issue. In that case it seems a like a video card hardware or drivers (this one is less likely, since I assume you already tried various driver versions when troubleshooting BSODs) issue.
 
Yea im still getting MINOR crackling without the Vcard when i look at dpc latency checker i never move out of the green even when the crackling does happen and says this machine should be able to handle the streaming of real time audio without drop outs. LatencyMon though says Your system appears to be having trouble handling real time audio and other tasks. You are likely to experience buffer underruns appearing as drop outs clicks or pops. one problem may be related to power management disable cpu throttlinh setting in control panel and bios setup. And highest for total executions is ndis.sys then latencymon itself then usbport.sys. I will run xperf next and update you then
 
I ran xperf compressed the file to a .rar but its 8.52mb which i believe is above the upload limit for .rars
 
If im supposed to be looking at DPC/ISR duration by module its the same as latency mon with ndis.sys and usbport.sys as the higest
 
ok video card back installed, didnt stay black after windows screen this time but crackling is back and worse then without it. latencymon has dxgkrnl.sys and nvlddmkm.sys as highest total executions and running xperf then looking at DPC/ISR it shows the same 2 at the top
 
Lasty,

please compress and upload both (one with integrated VGA and one with Nvidia) XPERF logs to SkyDrive, pasting the link here.

Thanks.
 
Regarding the first log:

The DPCs here are really low (less than 5% per CPU) and they are not what's causing these small audio glitches you mentioned. The problem is that Chrome is talking almost all CPU time, resulting into 100% CPU usage, which cause audio glitches. To be more specific, I see that pepflashplayer.dll component is responsible for that CPU usage inside Chrome. This can probably be explain by the fact that you are using a built-in GPU, which does not support hardware video decoding inside Flash, putting all the load to the CPU.

Regarding the second log:

The DPCs seem to be higher than usually, above 5% per CPU with a spike to 10% for some time. Not surprisingly, nvlddmkm.sys driver is behind this. There's not really much I can suggest to resolve this apart from making sure you have the latest drivers released last month and maybe trying to use Nvidia Control Panel to tweak some settings (like choosing performance instead of quality). Anyhow, since I said earlier, if you had issues with this card since the beginning, it's likely it might be a hardware issue.
 

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