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Windows 7: High DPC/IR cpu from Network Usage

05 Sep 2011   #1

Windows 7 Pro x64
High DPC/IR cpu from Network Usage

I have noticed when Iam downloading at full speed of 1.8MB/s on Wifi or LAN there is high DPC/IR (Deferred Procedure Calls and Interrupt Requests) CPU usage - and when transferring files in or out to USB hdd.. i sometimes get pops & clicks in audio too - the CPU is a Turion 1.8Ghz x2 with 1Mb L2 cache and 2Gb of ram, DPC/IR can only be seen using Resource Monitor in windows 7 (type 'resource monitor' into startsearch) or using Process Explorer software, I dont know much about DPC/IR but as far as Im aware it handles errors or something like that and I was told it should never even go beyond 1% cpu usage - its more noticeable on laptops as these have CPUs that arent as powerfull as desktops and have wifi, it seems to be worse with wifi. it causes latency problems in windows too and things like audio playback get pops & clicks and windows & apps become sluggish.

What brought it too my attention was the CPU fan on my laptop was on all the time and windows seemed to be sluggish when I was downloading even though uTorrent was just using 3-5% CPU, I noticed the total at bottom of Task Manager seemed to be more than what would tally up in the window, it was when i used resource monitor that I seen it.

WiFi @ 1.8MB/s = 10-15% DPC/IR cpu usage
LAN @ 1.8MB/s = 5% DPC/IR cpu usage
Copying Files to USB HDD = 15% DPC/IR cpu usage (this test was odd as it was some time ago i done this one, but I remember it was either IN or OUT that had the increase, probably IN (and OUT was <1%) , I tried SDcard too and got varying results)

ive even seen it max at 40% when downloading on wifi and copying a file in/out too usb hard-drive at the same time...that is definitely not normal behavior

another problem I have with my Atheros wifi card is that it peaks and troughs with the download speed and when it troughs the internet is slow almost unresponsive, but i dont think thats related and will start seperate thread for that

after searching the internet it appears that many others have this problem in Windows 7 and is related to their network driver, many seem to have it much worse than me too.. I ran some program a while ago that monitors and tests to see whats causing it and it said it was NDIS.SYS which is the networking driver in Windows 7 (I think) - at first I thought it was related to Atheros Wifi driver but its not as ive seen many people with other drivers, plus it happens on my LAN which is realtek

I think everyone suffers with this in windows 7 and that its a bug, those with powerfull CPU's and using LAN probably wont notice it , but those with sub 2Ghz laptops and Wifi should if they look for it.

Has anyone esle had this problem and if so found a fix for it?
I came across a post on MS TechNet of someone else with same problem and they were given a link to a MS page that had a fix for it .."hotfix for 20% decrease in performance when high network usage" - I downloaded it but it wouldnt install saying my system was not compatible or some bull...i had the x64 win7 version too.. further on his post MS staff offered to have a look at it at cost of $300...needless to say that was the end of the post.

looking forward to replies :)

My System SpecsSystem Spec
02 Jan 2012   #2

Windows 7 Pro x64


Windows 8 still has this problem too
My System SpecsSystem Spec
30 Jul 2012   #3

Windows 7 Pro x64

I cant believe that NOBODY else can see this happening on their windows 7 machines? its happened on EVERY windows 7 machine that uses Wi-Fi and downloads in background... I suppose the more powerfull the processor the less your gunna notice it - but even now on my 3Ghz P4 PC I can see extra 25-30% CPU usage from DPC/IR - i couldnt even play a Youtube video while downloading at 1.6MB/s cos the CPU could not cope - YES the video was already buffered, it was playing but clicking and cutting out..

MS have NOT sorted it in W8 either as I tested a copy
My System SpecsSystem Spec

05 Feb 2014   #4

Windows 7 64 bt Home Premium


Any Up Dates with this on going problem ?

My System SpecsSystem Spec
07 Feb 2014   #5

Windows 7 Pro x64

nope - simply buy a more powerfull computer to help - ive since stopped using the affected laptop, I now have a core-i5 PC and have not tested it on this, waste of time as there will be no fix anyway as its not being recognised as an issue when it clearly is
My System SpecsSystem Spec
08 Feb 2014   #6

Windows 7 64 bt Home Premium

I spent some time on trying to stop the dropouts, crackles etc traced it down to the Atheros AR938 x Wireless Network Adaptor.

There are some advanced settings for the Atheros AR938 but as yet I am unable to find out how they should be set, below are how mine are set but are they correct ?

802.116 = Long & Short
Adhoc IIN = disable
Dynamic Mimo Power save= disable
Network Adress= not present
Receive Buffer= 256
Scan Valid Interval = 60
Transmit Buffer = 512

So I just disable it which is a pain to keep doing.

My System SpecsSystem Spec
08 Feb 2014   #7

Windows 7 Pro x64

the problem is the NDIS.SYS driver which controls the network, ive been told its poor driver code thats causing the issue, mine is Atheros to but ive seen it on other brands of wi-fi... on LAN too but less so, on our laptop (2Ghz x 2 AMD) it would use 20% CPU on IR/DPC when downloading at 1.8MB/s (15Mbps) and 5% CPU when doing the same on LAN (Realtek) ...something not right there... and ive been told its bad drivers... but like I say ive tried every driver there was for the card AND tested the theory on loads of other laptops with Intel/Realtek wifi cards and results are the same (scaled with their CPU power)
My System SpecsSystem Spec
08 Feb 2014   #8

Win-7-Pro64bit 7-H-Prem-64bit

What type of security is installed,
Which browsers are being used,
Which isp what type of router/ modem ?
Troubleshooting for win-7,

Have you looked at this thread ?
Ultimate Router Guide: Optimize Security & Performance
My System SpecsSystem Spec
08 Feb 2014   #9

Microsoft Community Contributor Award Recipient

Win 7 Home Premium 64bit Ver 6.1.7600 Build 7601 - SP1

It sounds like for what ever reason, and there are a few see Step 3 in the second link, your machines are switching out of DMA mode and reverting to PIO.

See if these two sites might help:
Check Your IDE Transfer Mode To Make Your PC Faster

This link comes from the first comment Paul Leclerc made at the above link:
DMA reverts to PIO | Windows Problem Solver

This second site offers a resetdma.vbs script in Step 1 or you can do the reset manually in Step 6.

It is also much more comprehensive than the first, but the first still has value.
My System SpecsSystem Spec
08 Feb 2014   #10

Desk1 7 Home Prem / Desk2 10 Pro / Main lap Asus ROG 10 Pro 2 laptop Toshiba 7 Pro Asus P2520 7 & 10

From the first post you mention the laptop fan was running all the time - well as a matter of course it will just depends on what speed idling or flat out?

What are the temps on the laptop? as it seems to me like it needs a darn good clean out.
My System SpecsSystem Spec

 High DPC/IR cpu from Network Usage

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