High DPC latency (ACPI.sys) on a new XPS 15 (clean install)

B-M · May 24, 2022

Hello

I got a new XPS 15 9520, and am experiencing high DPC latencies caused by ACPI.sys (1.5 - 2.5 ms, checking with Latency Mon).
I did a clean Win11 install. Right after the install, the numbers look ok, but then Windows Update starts to install drivers and the latency goes up.

Bios is up to date.

I found threads for older Windows, where it was suggested to use xperf to trace down the culprit, however these instructions don't seem to work on Win11 (when trying to stop the trace I get an error message).

Any help would be appreciated.

xrobwx71 · May 24, 2022

Please follow the guidance here: Video STUTTERING, Audio CRACKS/POPS and dpc/isr LATENCY (posting instructions)

You can post back here. You don't have to create another thread.

B-M · May 24, 2022

Thank you for your reply. I tried this, but when attempting to stop the trace with

Code:

xperf -d "%userprofile%\Desktop\trace.etl"

I get the following error message:

xperf: error: NT Kernel Logger: The instance name passed was not recognized as valid by a WMI data provider. (0x1069).

B-M · May 24, 2022

Ok, it seems that whenever I start LatencyMon while xperf is running, I get this error message. So I captured a trace without running LatencyMon.

Trace: trace.zip
Sysnative BSOD Collection: SysnativeFileCollectionApp.zip
Speccy: http://speccy.piriform.com/results/pPKogrDIIKhTxDbJNrMbccK

B-M · May 26, 2022

Update: I noticed that the spikes seem to happen while using the touchpad. So I connected a Bluetooth mouse and disabled the touchpad in device manager. Now the highest DPC is ntoskrnl.exe with just under 0,9 ms. APCI.exe is down to 0,4ms. Not great overall (my old Dell with an 6820HQ managed everything below 0,5ms), but already a lot better.
Now I would obviously prefer being able to use the touchpad, are there any alternative drivers that I could try? Dell doesn't supply one, I suppose its just the MS Precision driver. I didn't install it manually, it installed with Windows Update. Which also explains why at the beginning just after installing Windows, the number would be ok.

xrobwx71 · May 27, 2022

Can you roll back the driver? If so, what happens?

B-M · May 29, 2022

Sorry for my late reply. The option to roll back the driver is greyed out. I imagine because before WU downloaded the precision driver, there was no real driver installed. While I could use the touchpad for moving the cursor and maybe tapping (I don't remeber for sure), scrolling didn't work, nor did any other milti-finger gesture.

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High DPC latency (ACPI.sys) on a new XPS 15 (clean install)

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