DPC Latency Checker

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Svet

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Thesycon's DPC Latency Checker is a Windows tool that analyses the capabilities of a computer system to handle real-time data streams properly. It may help to find the cause for interruptions in real-time audio and video streams, also known as drop-outs. The program supports Windows 2000, Windows XP, Windows XP x64, Windows Server 2003, Windows Server 2003 x64, Windows Vista, Windows Vista x64.

More information and download:
http://www.thesycon.de/deu/latency_check.shtml
 

overnightchatter

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How long do i run DPC Latency Checker is enough for test. I ran it 20 minutes and rarely the Current Latency reachs over 2000 and max is 2300. Does my system have Latency Problem ? Thank you.
 

Svet

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Status is shown during checking, example:
"This machine should be able to handle real-time streaming of audio and/or video data without drop-outs."

Spikes example:

Follow the link above for details.


 

ex_forum_user_3

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I have the same as Svet has, but it's an AMD CPU.
I get to max 988 when defragging, cleaning disk and playing Red Alert 2 all the the same time ;)
 

Conditioned

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Heres how to check for dpc problems ( full creds to nolay on competing mobo vendors homepage):

Step 1) Download and install the Microsoft "xperf" tool. It's in the [http://msdn.microsoft.com/en-us/performance/default.aspx]. It's small, just a few megabytes. This tool will tell you what actually caused the spike you see in dpclat.

Step 2) Run the xperf tool to start watching what's causing the spikes. Open a command line console, and then type:

xperf -on Latency

Step 3) Allow the xperf tool to collect information for 5 minutes while you use your computer. After you feel you did a little monitoring, then stop it. Type:

xperf -stop

This creates a C:\kernel.etl file which is a log of the DPC's and ISR's taking place during that timeframe.

Step 4) Create a report file so you can see where the spikes came from. Type:

xperf -I \kernel.etl -symbols verbose -a dpcisr > latency_report.txt

This will create a report file called latency_report.txt in whatever folder you're in.


Now, you need to interpret this file. It shows you a list of the maximum latencies produced by each driver. A DPC of 512 means one of your drivers/devices was blocking all processing on your system for 512us. All you have to do is find the one that says "512" on it.

Here is an example of one of my report.txt's:




In this case, dxgkrnl.sys is an Nvidia mobile GPU driver, and its power management is causing massive latency spikes in the system.

Looking forward to hearing your results if you have 10 mins to test this.

If anybody else can test this too, it would be awesome. I think these EVGA boards are high quality in the latency department, we just gotta find the device that's throwing the spikes.

Thanks a million,
- Nolay


I currently have a Msi z68 gd80 b3. The dpc stands pretty consistently around 30-70. I tried a Asus P8z68-v pro / gen3 where it bounced back and forth a lot.
 

FATAL1TY

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this program haven't compatibility with Win8 and Win8.1

what else i can use to check the latency?



 
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