High DPC Latency

Shinobi_32 · Sep 13, 2013

Hi everyone,

For the past few months i have had audio crackling problems on my Win 7 OS. In that time i have tried all kinds of things to correct the problem which i wont go into here, but today just as i had almost given up, i came across a great thread on your site titled 'How to Diagnose and Fix High DPC Latency Issues with WPA (Windows Vista/7/8)' so i checked the DPC Latency Checker and their it was, the problem in all it's glory lol.

http://i.imgur.com/4NZ3qlV.jpg

So after finding i had a high latency issue, i continued with the tutorial, and ran the Windows Performance Analyzer.

http://i.imgur.com/SHnoJyt.jpg

As you can see from the above link, the highest latency appears to be coming from a driver which is Unknown.
This is as far as I've been able to get on my own and so was hoping one of you guys could help me find the solution.

I also ran LatencyMon. Here's the links:

http://i.imgur.com/ESUvrjI.jpg

http://i.imgur.com/29NpBD2.jpg

Thanks
Lee :)

satrow · Sep 13, 2013

Welcome to Sysnative, Lee!

At first glance, it looks like something network -related, maybe drivers, maybe something more suspicious - could just be an old security software remnant stuck there somewhere.

Can you carefully read and then follow the instructions for BSOD data collection, it should give us all a better handle on your machine, software and errors logged, etc. Attach the needed zipped folder back here oce you've done it. Don't forget to run it as Administrator from the location given: https://www.sysnative.com/forums/bs...d-posting-instructions-windows-8-7-vista.html

Shinobi_32 · Sep 14, 2013

satrow said:
Welcome to Sysnative, Lee!

At first glance, it looks like something network -related, maybe drivers, maybe something more suspicious - could just be an old security software remnant stuck there somewhere.

Can you carefully read and then follow the instructions for BSOD data collection, it should give us all a better handle on your machine, software and errors logged, etc. Attach the needed zipped folder back here oce you've done it. Don't forget to run it as Administrator from the location given: https://www.sysnative.com/forums/bs...d-posting-instructions-windows-8-7-vista.html

Hi,

Thanks for the reply. Just before i was about to gather together everything you asked for in your last post, i decided to uninstall my internet security software to check if that's causing the latency issues. Well in short IT WAS. I can't believe it after everything i tried that was all i had to do.

Check this baby out.

http://i.imgur.com/C81P3zE.jpg

That image is taken with new and different internet security software too.

So for now at least I'm going to consider this problem as FIXED!!! I've been streaming audio from youtube for the past 30mins and no pops present...

I just want to thank you guys for your help, especially 'niemiro', as if it wasn't for his tutorial thread i would have never tried to test my latency.

A couple of days ago i ordered some top of the range speakers too, thinking that would somehow magicly fix the issues, but i suppose it's not to bad because i now have some top of the range speakers lol.

Thanks again
Lee :)

satrow · Sep 14, 2013

Great news, Lee!

Really pleased you found the problem :)

I'll pass on your note to niemiro, too!

Vir Gnarus · Sep 16, 2013

You can tell it's the avast! Firewall NDIS filter service driver. You were getting thrown off by misinterpreting the Actual Duration column in the output. That column only tells you the entire cumulated time for that specific driver during the logging. So what it's just telling you was that overall was that the Unknown was DPC active - very active - during the logging. However, now look at the adjacent columns, Max Actual Duration and Avg Actual Duration, as those tell you the longest time it took to complete a DPC and the average time it took to complete a DPC, respectively. With them, you can tell that while Unknown driver did show up unusual peak in the Max with a DPC completion that took over 100ms, overall it doesn't look too bad, and it looked like for the most part DPCs were being completed in pretty short times, around 10-20ms.

Now what really stood out was under tcpip.sys, which involves network activity. It shows in its row that something was holding it up and there was a max actual DPC duration of 2.4 seconds! Wow! That took forever to complete! So what's the problem here? Well if you see it's been expanded to show the drivers under it, and it's quite evident the culprit standing out like a sore thumb: aswNdis2.sys - the avast Firewall NDIS driver - was responsible, with an average DPC completion time of 2.3 seconds over a span of 79 DPCs (determined by the Count column). Since this is an NDIS driver, it also coincides with the ugly spike in ndis.sys too.

So it's evident avast driver was responsible, but why was it? Unfortunately with the info you've given us we can't tell that far. It may be a bug in that version of the driver and that you need to update it. Or it could be that it too was held up by something like waiting on disk I/O. Whatever the case, it was taking its sweet time, and fortunately it seems that removing it fixed the problem. Just make sure to replace it with some other AV software!

fifa1004 · Dec 21, 2015

idk how recent this thread is but i am having a similar problem i posted about it on the forum if someone could help me out.

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High DPC Latency

Shinobi_32

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satrow

Moderator, BSOD Kernel Dump Senior Analyst

Shinobi_32

New member

satrow

Moderator, BSOD Kernel Dump Senior Analyst

Vir Gnarus

BSOD Kernel Dump Expert

fifa1004

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