deferred procedure calls DPCs - PC hangs

By detrunks
Jan 25, 2006
  1. Every now and again my PC hangs. Process explorer shows DCPs using 100% of the CPU. Why does this happen and how can I troubleshoot it please?

    Thx in adavance for any pointers!!
  2. jobeard

    jobeard TS Ambassador Posts: 9,148   +597

    use <ctl><alt><del> to bring up the task monitor.
    under the VIEW menu, 'show kernel' times. Large kernel/DPC times suggest heavy
    I/O activity. Are all your devices performing correctly?
  3. detrunks

    detrunks TS Enthusiast Topic Starter Posts: 153

    no kernal view option

    I have the 64-but version & there is no kernal view option. There are options for I/O read/write/bytes etc...

    Anyhow, once the CPU is at 100% I can't open proc_ex to see the kernals (the pc is hanging).

    How would I know if all my devices are working correctly?
  4. WeAreZilla

    WeAreZilla TS Rookie

    Hello everyone,
    Thought I'd share my experience with spiking Deferred Procedure Calls (DPCs). My spikes were happening at about 10 second intervals, shooting to 35-55%, then back down to zero or near zero. Although I chased all the hardware demons suggested at several sites, it turns out to be software related. I'm very curious if anyone has the same issue.

    As mentioned, I sorted out all my hardware first. This included replacing the video card and sound card, and verifying proper drivers and functionality of the NIC, modem, and USB 2.0 cards. Also checked drivers and settings in my wireless router. All with no success in resolving the spikes.

    Then I suspected a software issue because of the cyclic nature of the DPCs and the first stop was my antivirus/firewall software. I use Trend Micro Internet Security 2007 (PCC 15) but other versions such as PCC 12 (2005) or 14 (2006) may have similar functionality. My results are definitive and repeatable:

    From the Main Console > Virus & Spyware Controls > Protection Against Viruses, turn off Network Virus Monitor. (I should mention that I was going through all of these settings quickly and didn't initially notice the DPC spikes had disappeared. By that time I had disabled Mail Monitors as well, but re-enabled them right away, narrowing it down to Network Virus Monitor.)

    Well, there you have it, no more DPC spikes, no more skipping sounds, no more system slow downs. I should note that I really enjoy using Trend Micro products, and have even done some beta testing for them in the past. In general their products do an excellent job for me, without bogging down my system like some other security software I won't mention.

    Let me know if this situation applies to you as well and I will report it to Trend Micro. Good luck.
  5. higgrobot

    higgrobot TS Rookie

    The same thing started happening to me, i had a look at what services were running and noticed auto-update had been turned back on? strange i remember specifically turning that off in favour of manually updating when i choose too. I suspect it may have been turned back on when i installed media player 10? anyway, after disabling the auto-update in service's and rolling back media player in favour of whatever version it was before, everything seems fine. Hope that can help someone, feels good to be in control of my mouse and have my cpu back.
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