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How to get the cause of high CPU usage by DPC / Interrupt


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which xperf version did you use? Some data are missing. Also add -BufferSize 2048 at the first command. Some buffers are not included in the trace.

Also install Windows 7 Sp1 + all updates. You're still using Windows7 RTM from 2009 which is now over 2 years old. That is enormous age for a software.

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i've downloaded the latest win SDK and installed xperf according to your tut... should be the latest then right? i've forget to do this buffer thing...

and i will get all win7 updates/sp1 if you say it is a real help... a support-guy at my music-store told me not to update anything after a clean new win isntallation when i want to use the pc as DAW only...

i download all this stuff now... its 297mb... should be quite quick

updates 30/94 is done... which ETL file should i redo with buffer size set correct? the CPU or the interrupt_CPU?

Edited by adlib
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ok, it worked.


Total = 5287 for module ndis.sys
Elapsed Time, > 4096 usecs AND <= 8192 usecs, 13, or 0.25%

So ndis.sys causes the spikes. This is network related. Update the athr.sys driver for your Atheros AR9285 Wireless Network Adapter

And install the Sp1, you use Build 7600.

Edited by MagicAndre1981
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i've done all the updates (atheros seems to be the latest driver already) and now LatencyMon shows some other driver files which causes latency!! :( ntoskrnl.exe, dxgkrnl.sys,...

traces follow in some minutes...

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No, it is still NDIS:

Total = 1614 for module ndis.sys

Elapsed Time, > 1024 usecs AND <= 2048 usecs, 4, or 0.25%

Elapsed Time, > 2048 usecs AND <= 4096 usecs, 0, or 0.00%

Elapsed Time, > 4096 usecs AND <= 8192 usecs, 5, or 0.31%

And this happens when you use Opera. Does it happen with other browsers, too?

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ok, thx

when i've uploaded the first traces opera wasnt even installed... i installed opera yesterday but its not difference if i use ie8, ie9, opera or no browser at all... the ndis caus some spikes even when there is no internet usage at all... atheros is updated and there are no more windows updates available. what to do next? :(

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hi andre

thx for your help so far... any more ideas?

i've tried a lot of different drivers for the atheros this weekend... odler drivers, new drivers... no difference. as soona s the atheros 9285 driver is activate ndis.sys creats latency spikes. the same for the battery... sony drivers and win7 drivers both make acpi.sys create latency. when i deactivate atheros and battery in the device manager the laptop runs perfect... really annoyed with this situation :(

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Hi Magic Andre! I've been following this thread for the last few days and I gotta say, your directions on how to find the driver that's hogging my cpu was really helpful. i found out that it was the ACPI.sys as well as a lot of system interrupts but I have -no- idea how to fix it. This is a brand new home build computer with a clean install of Windows Vista x64 and it was working fine. It wasn't until I upgraded to Windows 7 home premium x64 that I started going really really slow (understatement of the year) and I can't figure out why.

Processor: AMD Phenom II x2 555

Motherboard: Biostar N68s3+

Graphic card: Radeon 5570

All drivers and Bios are up to date and I have downloaded SP1 and the other windows 7 updates with so far no success. My .etl file below.

https://rapidshare.com/files/3811000101/DPC_Interrupt.etl

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@adlib

looks like you have the same ACPI battery issue like eminememinem. Try to install the battery and let Windows install the drivers again.

About the atheros 9285, atheros makes cheap chips which work, but which are not the best you can get. Is the WLAN module replaceable or fixed on the laptop motherboard? Maybe you can switch to a different module from Intel.

Edited by MagicAndre1981
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Thanks for this,

I used Xperf before in past and it was NDIS.SYS driver (windows 7 64x)... it is Atheros AR5005G wireless adapter running on latest versions for win7 it still does the same thing, I get this CPU usage when I copy files out to USB drive too - if I do both that and download files via wifi at 16Mbps then DPC/IR uses as much as 30 - 40% of my 1.8Ghz dual-core chip on laptop

WIFI downloading at full speed = 10-15% DPC

LAN downlaoding at full speed = 5% DPC

Copying files to USB HDD - 10-15% DPC

Both WIFI downloading at full speed and Copying files to USB HDD = 30-40% DPC

EDIT: actually just checking it again (as its been a while) its nowhere near as bad as that now, for downloading on wifi its about 2-5% DPC/IR - but soon as I copy files to or from USB drive it spikes to 15% DPC/IR usage.. I wonder if its the wifi driver as ive been having problems with that too and been changing and trying different ones, the one i settled on was v 8.0.0.305 (Feb 2010) (I was having problems with speed peaks and troughs, latest v9 drivers just didnt work at all for uploading) - this driver seems to work best and ive tried all latest ones back over to this one.

seems ATHEROS wireless drivers just do not like Windows 7 full stop.

- I have seen and heard of this problem on other computers with Intel chipsets and other things causing the same problem. for me it seems to be a bug in windows 7.

Edited by snadge
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