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System interrupts, Latency, HDaudbus.sys


New member
Mar 5, 2017
Hi Everyone,

I have problem with 'system interrupts' process, it takes ~20-50%. It's new pc and fresh system installed.

LatnecyMon results:

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 or more ISR routines that belong to a driver running in your system appear to be executing for too long. One problem may be related to power management, disable CPU throttling settings in Control Panel and BIOS setup. Check for BIOS updates.
LatencyMon has been analyzing your system for 0:03:00 (h:mm:ss) on all processors.

Computer name: KOMPUTER
OS version: Windows 8.1 , 6.3, build: 9600 (x64)
Hardware: MS-7A72, MSI, B250 PC MATE (MS-7A72)
CPU: GenuineIntel Intel(R) Core(TM) i5-7600 CPU @ 3.50GHz
Logical processors: 4
Processor groups: 1
RAM: 16344 MB total

Reported CPU speed: 3504 MHz
Measured CPU speed: 1 MHz (approx.)

Note: reported execution times may be calculated based on a fixed reported CPU speed. Disable variable speed settings like Intel Speed Step and AMD Cool N Quiet in the BIOS setup for more accurate results.

WARNING: the CPU speed that was measured is only a fraction of the CPU speed reported. Your CPUs may be throttled back due to variable speed settings and thermal issues. It is suggested that you run a utility which reports your actual CPU frequency and temperature.

The interrupt to process latency reflects the measured interval that a usermode process needed to respond to a hardware request from the moment the interrupt service routine started execution. This includes the scheduling and execution of a DPC routine, the signaling of an event and the waking up of a usermode thread from an idle wait state in response to that event.

Highest measured interrupt to process latency (µs): 199,013699
Average measured interrupt to process latency (µs): 5,997418

Highest measured interrupt to DPC latency (µs): 177,680365
Average measured interrupt to DPC latency (µs): 2,597537

Interrupt service routines are routines installed by the OS and device drivers that execute in response to a hardware interrupt signal.

Highest ISR routine execution time (µs): 554791,380422
Driver with highest ISR routine execution time: HDAudBus.sys - High Definition Audio Bus Driver, Microsoft Corporation

Highest reported total ISR routine time (%): 6,571456
Driver with highest ISR total time: HDAudBus.sys - High Definition Audio Bus Driver, Microsoft Corporation

Total time spent in ISRs (%) 13,108723

ISR count (execution time <250 µs): 77997351
ISR count (execution time 250-500 µs): 0
ISR count (execution time 500-999 µs): 0
ISR count (execution time 1000-1999 µs): 0
ISR count (execution time 2000-3999 µs): 0
ISR count (execution time >=4000 µs): 0

DPC routines are part of the interrupt servicing dispatch mechanism and disable the possibility for a process to utilize the CPU while it is interrupted until the DPC has finished execution.

Highest DPC routine execution time (µs): 270,130708
Driver with highest DPC routine execution time: tcpip.sys - Sterownik TCP/IP, Microsoft Corporation

Highest reported total DPC routine time (%): 5,496054
Driver with highest DPC total execution time: HDAudBus.sys - High Definition Audio Bus Driver, Microsoft Corporation

Total time spent in DPCs (%) 0,062792

DPC count (execution time <250 µs): 341695
DPC count (execution time 250-500 µs): 0
DPC count (execution time 500-999 µs): 1
DPC count (execution time 1000-1999 µs): 0
DPC count (execution time 2000-3999 µs): 0
DPC count (execution time >=4000 µs): 0

Hard pagefaults are events that get triggered by making use of virtual memory that is not resident in RAM but backed by a memory mapped file on disk. The process of resolving the hard pagefault requires reading in the memory from disk while the process is interrupted and blocked from execution.

Process with highest pagefault count: firefox.exe

Total number of hard pagefaults 2
Hard pagefault count of hardest hit process: 1
Highest hard pagefault resolution time (µs): 6,366438
Total time spent in hard pagefaults (%): 0,000001
Number of processes hit: 1

CPU 0 Interrupt cycle time (s): 87,980507
CPU 0 ISR highest execution time (µs): 554791,380422
CPU 0 ISR total execution time (s): 94,538534
CPU 0 ISR count: 77997437
CPU 0 DPC highest execution time (µs): 230,918379
CPU 0 DPC total execution time (s): 0,243487
CPU 0 DPC count: 250216
CPU 1 Interrupt cycle time (s): 0,842647
CPU 1 ISR highest execution time (µs): 0,0
CPU 1 ISR total execution time (s): 0,0
CPU 1 ISR count: 0
CPU 1 DPC highest execution time (µs): 270,130708
CPU 1 DPC total execution time (s): 0,081513
CPU 1 DPC count: 31691
CPU 2 Interrupt cycle time (s): 1,625785
CPU 2 ISR highest execution time (µs): 0,0
CPU 2 ISR total execution time (s): 0,0
CPU 2 ISR count: 0
CPU 2 DPC highest execution time (µs): 78,363014
CPU 2 DPC total execution time (s): 0,058310
CPU 2 DPC count: 31539
CPU 3 Interrupt cycle time (s): 1,720053
CPU 3 ISR highest execution time (µs): 0,0
CPU 3 ISR total execution time (s): 0,0
CPU 3 ISR count: 0
CPU 3 DPC highest execution time (µs): 72,554224
CPU 3 DPC total execution time (s): 0,069542
CPU 3 DPC count: 28250

I tried to disable devices in Devices manager to check what can cause the problem, but it showed nothing. Could anyone help me to solve this problem?




Staff member
Dec 31, 2013
World, Europe, Italy
Hi Kilroy. :welcome:

Would you try these steps?

In case you don't know how to open an elevated command prompt in windows 8.1, this is the simplest procedure: right-click windows start, click command prompt (admin).

  • Left-click on Start, type directly msconfig, press enter.
    Is the radio button on normal startup?
  • Launch this command from an elevated command prompt:
    dism /online /cleanup-image /checkhealth
    Do you get my same result?
    Read More:
  • Advanced disk cleanup with cleanmgr:
    • Open an elevated command prompt
    • Type cleanmgr /sageset:1 and press enter.
    • Select all the options, or leave unticked the ones you prefer.
    • Type cleanmgr /sagerun:1 and press enter
    • Let it work until it finishes.
  • Launch this command from an elevated command prompt:
    sfc /scannow
    If you get the following message:
    Windows Resource Protection found corrupt files but was unable to fix some of them. Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log
    Read Windows Update Forum Posting Instructions (click) and provide the necessary (and missing) informations to the experts.I.e., you should:
    • export and zip/compress the entire CBS folder on your desktop
    • open a new topic in the windows update sub-forum (in sysnative.com)
    • attach that zipped file to that new topic
    If the CBS compressed folder will be too large, you can check the second post on that thread (to use the sfcfix tool with a script) or you can use a (possibly fast) web service like MS OneDrive, Google Drive, DropBox, Box, Mega, Apple iCloud, Amazon Cloud Drive, and so forth...
    Instead if you get the following messages, go to the next step:
    Windows Resource Protection did not find any integrity violations
    Windows Resource Protection found corrupt files and successfully repaired them. Details are included in the CBS.Log %WinDir%\Logs\CBS\CBS.log
  • Defragment your system drive (using windows default defragmenter). Steps:
    • Open an elevated command prompt
    • Type defrag c: /h and press enter
    • Wait until it finishes
  • Check you system partition, then post the result here. Steps:
    • Open an elevated command prompt.
    • Type chkdsk c: /b and press enter.
    • You'll get:
      The type of the file system is NTFS.
      Cannot lock current drive.
      Chkdsk cannot run because the volume is in use by another
      process. Would you like to schedule this volume to be
      checked the next time the system restarts? (Y/N)
    • Type Y and press enter.
    • Then restart/reboot and wait until it finishes this check.
    • To find chkdsk result:
      • Open an elevated command prompt
      • Copy/paste this command and press enter:
        wevtutil qe application /c:1 /rd:true  /f:text /q:"*[System[Provider[(@Name='Microsoft-Windows-Wininit')]]]" > "%userprofile%\desktop\ChkDskLOG.txt" & notepad "%userprofile%\desktop\ChkDskLOG.txt"
      • It should create chkdsklog.txt on your desktop and open it: paste its content here.
      • If the command won't work, type eventvwr, press enter, in the event viewer window double-left-click Windows Logs to expand it, left-click Application, double-left-click the information event with source wininit, copy its content and post it here.
After all those operations, reboot your machine and see if the problem persists.

If the problem persists:

  • Please provide answers for (answer the best that you can):
    • System Manufacturer?
    • Laptop or Desktop?
    • Exact model number (if laptop, check label on bottom)
    • OS ? (Windows 10, 8.1, 8, 7, Vista)
    • x86 (32bit) or x64 (64bit)?
    • Service pack?
    • What was original installed OS on system?
    • Is the OS an OEM version (came pre-installed on system) or full retail version (YOU purchased it from retailer)?
    • Age of system? (hardware)
    • Age of OS installation?
    • Have you re-installed the OS?
    • CPU
    • RAM (brand, model, which slots are you using?)
    • Video Card
    • MotherBoard - (if NOT a laptop)
    • Power Supply - brand & wattage (if laptop, skip this one)
    • What security software are you using? (Firewall, antivirus, antimalware, antispyware, and so forth)
    • Are you using proxy, vpn, ipfilters or similar software?
    • Are you using Disk Image tools? (like daemon tools, alcohol 52% or 120%, virtual CloneDrive, roxio software)
    • Are you currently under/overclocking? Are there overclocking software installed on your system?
  • Retrieve System Information, using speccy
    1. Download Speccy portable - actual version 1.29.714 (click), unzip/decompress it and put it on your desktop.
    2. When the program opens, it will retrieve some information regarding your system.
    3. Once it's done, select the File menu and choose Publish snapshot. Answer Yes to the confirmation message.
      (Or generate a log in your pc, if you prefer to not publish the snapshot for some reason)
    4. On the next screen that comes up, choose the Copy to Clipboard button and paste this link in your next reply.
      (Or upload here the generated log, in case you didn't publish the snapshot)
  • Facultative System information log (if previous point fails for some obscure reason)
    The following command should be run from an elevated command prompt.
    It should generate a log, named MsInfo.nfo, on your desktop, after some time (few seconds or minutes).
    Read More:
    msinfo32 /nfo msinfo32 /nfo "%userprofile%\desktop\MsInfo.nfo"
    (Then upload it here)
  • Download and install the Windows Performance Toolkit - Windows Assessment and Deployment Kit (Windows ADK) for Windows 8.1 Update - adksetup.exe 1.36MB (click):
    Read More:
    Then open an elevated command prompt (right-click on the windows start button on bottom-left corner, left-click Command Prompt (Admin)) and launch these commands:
    Read More:

    You can also read the original tutorial/guide and its following posts for more informations:

    How to Diagnose and Fix High DPC Latency Issues with WPA (Windows Vista/7/8) (click) (by Niemiro)
Last edited:


New member
Oct 8, 2017
To fix this, you need to switch "High Definition Audio Controller (Microsoft)" to MSI mode. In the registry in the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI""YOUR HD AUDIO PARENT""\DeviceParameters\Interrupt Management\MessageSignaled\InterruptProperties\ "MSISupported" Change to "0x00000001"
YOUR HD AUDIO PARENT see in Device Manager\Sound, Video and game controllers\hdaudio, realtek and other\Properties\Details\Parent


Staff member
Dec 31, 2013
World, Europe, Italy
Hi PowerFulls. :welcome:

Could you explain why this fix should work? We only have got very few information about OP's system.
It could easily apply to all DPC threads.
Does it work on your machine only?
Is it an empiric fix?
Or do you know it worked on other machines?

I found that entry in
Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI\VEN_8086&DEV_1C20&SUBSYS_04921025&REV_05\3&11583659&0&D8\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties

(REG_DWORD) set to 0
Where VEN_8086&DEV_1C20&SUBSYS_04921025&REV_05\3&11583659&0&D8 should be specific for my machine (and maybe some other machines).
I found that after I examined all the ten keys under PCI, but I also found it following your directions: Device Manager\Sound, Video and game controllers\Realtek High Definition Audio - right-click it, properties, details tab, and selected Parent under the drop-down menu property.

(I'm using Win10Std x64 v1703 b15063.632, i.e. fully updated at today)


New member
Oct 8, 2017
On some PCs, another device connects to the same IRQ with the hdaudio, so there is a strong delay. change in the registry MSISupported = 1 takes the IRQ to another mode.
I think (maybe) similar actions will help with delays from other devices, for example nvidia, lan ...
This problem is on some motherboards that connect multiple devices to one IRQ.
Delays from HDAud and Wdf01000.sys, at least 4 pc disappeared


New member
Jun 8, 2018
I have been reading the forum for several days over a couple of weeks to try and fix my problem. I zoomed in on the xperf DPC graph and the summary showed HDAudio.sys as a very small usage, but I googled anyway and here I am. To try MSI mode I had to add two keys and a value in regedit. I figured if it was not supported it would just ignore the changes. It did ignore the request to switch on MSI mode, but it gave HDAudio its own IRQ, where previously it shared an IRQ with five other drivers. (device manager->view resources by type->IRQ)

It fixed the problem!!!!! No yellow or red DCP bars and all green bars seem shorter. Thanks you.


New member
Jun 8, 2018
Hi paulf8080. :welcome:

Are you using windows 8.1 update3 x64?
Or another OS?
I'm still using win7 x64. My system is an Asus Z87I-deluxe with a Core I7. On board audio and HDMI audio. Another reason I looked at HD Audio is this video tweaks sound power management and it helped a little. YouTube

The zoomed in xperf DPC summary could maybe add an IRQ column to see if an IRQ appears twice in the window.

It is still OK and I am very happy.


Staff member
Dec 31, 2013
World, Europe, Italy
Good! To speed up things, from an elevated command prompt:
reg query HKLM\SYSTEM\CurrentControlSet\Enum\PCI\ /s /f hdaudbus
That command found this registry path in my machine (and obviously this will be different than other machines):
In device manager, Sound, Video and game controllers, Realtek High Definition Audio, properties, details tab, under the drop-down menu Property, I chose Parent, and I have that same string: PCI\VEN_1022&DEV_780D&SUBSYS_76621849&REV_01\3&11583659&0&A2
Read More:

Therefore in my case I had to use these other commands:
reg query "HKLM\SYSTEM\CurrentControlSet\Enum\PCI\VEN_1022&DEV_780D&SUBSYS_76621849&REV_01\3&11583659&0&A2\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties"
reg add "HKLM\SYSTEM\CurrentControlSet\Enum\PCI\VEN_1022&DEV_780D&SUBSYS_76621849&REV_01\3&11583659&0&A2\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties" /v MSISupported /t REG_DWORD /d 1 /f
The first one just checks if the value exists and how it is currently set.
The second one sets the value to 1.
Output (in Win10 v1803 b17134 x64):
Read More: