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DPC (Deferred Procedure Calls)
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dirbase View Drop Down
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Posts: 440 		Post Options Post Options   Quote dirbase Quote  Post ReplyReply Direct Link To This Post Topic: DPC (Deferred Procedure Calls)
    Posted: 29 December 2009 at 1:12pm
Maybe Kernrate would help.

Edited by dirbase - 09 January 2010 at 11:02pm
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andyint View Drop Down
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Posts: 5 		Post Options Post Options   Quote andyint Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2009 at 11:55am

Hi all,

I'm experiencing similar problems on a Windows XP x64 machine with a Intel Core 2 Quad CPU. When the system is idle, there is a workload of usually 8 - 10%, which according to Process Explorer is caused by deferred procedure calls. When starting Windows in safe mode, the CPU usage goes down to 0% when the system is idle, as expected. I thus assume that a device driver may be causing the problems, as reported by others. However, I have set up hardware profiles and disabled about any device I could, including the graphics card, without any success.

Any advice for tracking the source of the DPCs would be greatly appreciated. It seems tools such as xperf or RATTV3 are not applicable in my case since I am running Windows XP x64 and not Windows 7 or Windows XP x86.

Thanks a lot!
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molotov View Drop Down
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Posts: 17492 		Post Options Post Options   Quote molotov Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2009 at 11:32am
Hi ellockie,

Unfortunately, it seems that wireless devices or their drivers are not an uncommon cause for issues similar to what you report.  Good to hear you were able to get to the bottom of it!
Daily affirmation:
net helpmsg 4006
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ellockie View Drop Down
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Posts: 1 		Post Options Post Options   Quote ellockie Quote  Post ReplyReply Direct Link To This Post Posted: 24 October 2009 at 4:48pm
Thank you all for useful tips. I solved this problem!

I run abovementioned DPC Latency checker (free, http://www.thesycon.de/eng/latency_check.shtml) and switched off various deviced on my system in Device Manager.

The problem was with Dell Wireless 1505 Draft 802.11n WLAN Mini-Card.

No problem when it is disabled as I have cable connection with the router, but not sure if I'll be still connect with wireless laptops - don't know much about networking.

My system (1yr old):
Dell Studio (customised) with Intel® Core™ 2 Quad-Core Q9400 Processor
512MB nVidia GeForce 9800GT
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molotov View Drop Down
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Posts: 17492 		Post Options Post Options   Quote molotov Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2009 at 3:47am
note: moved jimvierling's discussion into its own topic:
Problem with DPCs, Interrupts
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net helpmsg 4006
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molotov View Drop Down
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Posts: 17492 		Post Options Post Options   Quote molotov Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2009 at 10:58am
The DPCs are sort of a stack that lies before the Interrupts
DPCs are used by device driver interrupt service routines to defer less time-critical activity and allow the ISR to complete as quickly as possible.
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net helpmsg 4006
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Temet View Drop Down
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Posts: 2 		Post Options Post Options   Quote Temet Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2009 at 10:52am
@molotov:

I am sure the KIS firewall is the cause. It didnt show up until the number of guarded programs reached the 600 mark. I could not make out another source, e.g. drivers, as I switched all of them off one by one - no different results altogether. The KIS was my last guess actually ;)

Also, the Kaspersky folks were pretty weak in their responses, like "uninstall SuperAntiSpyware", or, "send us that and that file for examination", where all of those files showed up perfectly clean at virustotal.com; the phone comment was like "security doesnt come free, you have to give something in return". Especially that comment was what nailed it for me, because it means they know it, they cant fix it, and they dont talk about it.

Good enough?

@JonMcP:
Looks very much like it, I would say. The connection between the firewall and the virusscanner means, every single packet of every used protocol is examined. If you cause traffic, this is where scanning time multiplies. The DPCs are sort of a stack that lies before the Interrupts, DPC usage by itself means there is already a congestion in progress.

Get the DPC latency checker (freeware, www.thesycon.de) and examine as has been said earlier in this thread. I'm no hardware pro myself and stll it gave me some good answers to improve on.

I would appreciate it if you post your findings here.

All the best
Temet
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JonMcP View Drop Down
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Posts: 6 		Post Options Post Options   Quote JonMcP Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2009 at 7:26pm
if it is KIS that causes the trouble, would that explain my DPCs being high only after several minutes of high bandwidth usage, and it returning to useable after a reboot?

I don't use KIS , i use ZoneAlarm; but since ZA = KIS, it would make sense to assume that if it is KIS, it is also ZA that causes the trouble.

I will try it myself and report back.
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molotov View Drop Down
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Posts: 17492 		Post Options Post Options   Quote molotov Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2009 at 6:58pm
Hi Temet,

Do you suspect the KIS firewall to be the cause, or simply affected by some other problem?
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net helpmsg 4006
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Temet View Drop Down
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Posts: 2 		Post Options Post Options   Quote Temet Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2009 at 10:32am
Hi there. Glad to have found you Big smile

Using DPC Latency Checker, I found a completely different explanation for high DPC percentage: It's the firewall of Kaspersky Internet Security 2009 (8.0.0.454 and also .506) that gets slower over time. The deactivation of the firewall proves it - the DPC Latency drops from a full 15000 microseconds to a mere 120 microseconds -- and all green ever after.

I sent this to the Kaspersky folks but they couldn't work it out as yet. It looks like the firewall gets sort of stuffed over time, but the effect apparently doesn't depend on actual usage of internet apps. Any Ideas?

Temet
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