Deferred Procedure Calls

Discussion in 'other software & services' started by Rainwalker, Oct 9, 2005.

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  1. Rainwalker

    Rainwalker Registered Member

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    I have looked and i am still not sure what DPCs are used for and if i am on a stand alone system, do i need it ?
     
  2. Bubba

    Bubba Updates Team

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    In case it helps....what causes you to ask this ?
     
  3. Rainwalker

    Rainwalker Registered Member

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    Bubba...i saw it running while looking at Process Explorer
     
  4. T772

    T772 Guest

    Interrupts and DPCs
    On Windows NT-based systems Process Explorer shows two artificial processes: Interrupts and DPCs. These processes reflect the amount of time the system spends servicing hardware interrupts and Deferred Procedure Calls (DPCs), respectively. High CPU consumption by these activities can indicate a hardware problem or device driver bug. To see the total number of interrupts and DPCs executed since the system booted add the Context Switch column. Another sometimes useful metric is the number of interrupts and DPCs generated per refresh interval, which you see when you add the CSwitches Delta column.


    hope this helps T
     
  5. Rainwalker

    Rainwalker Registered Member

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    Interesting......thank you.......what are Deferred Procedure Calls and being on a stand alone computer, can i safely turn it/them off ?
     
  6. Bubba

    Bubba Updates Team

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    Was the info you saw similar to the below pic ?

    Notice that it is not actually a process....similar to the one above it Interrupts(Hardware Interrupts)
     

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  7. gottadoit

    gottadoit Security Expert

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    Rainwalker,
    They are an integral and low level part of Windows and cannot be turned off
    They are different to Remote Procedure Calls (which also cannot be turned off) and it was probably Remote Procedure Calls that you were thinking about

    Some "light" reading
    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndevice/html/IRQL_Sched.asp
    http://msdn.microsoft.com/library/d..._07529fa6-0954-4b27-b610-99f465d2fbf3.xml.asp

    Regards
     
  8. Bubba

    Bubba Updates Team

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    One can see RPC's via Process Explorer :doubt:
     
  9. lotuseclat79

    lotuseclat79 Registered Member

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    Hi gottadoit,

    Please explain what happens when the Remote Procedure Call (RPC) service is stopped or disabled? Is this not the same as "turned off"? Re: WinXP!

    For example, Start->Run->services.msc->Ok
    Check status of Remote Procedure Call (RPC) and Remote Procedure Call (RPC) Locator services.

    If they are started, right-click on either one, select Properties, and if you are an Administrator account, you can modify the start type to Manual or Disabled.

    -- Tom
     
  10. Rainwalker

    Rainwalker Registered Member

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    @ Bubba.........yes, similar
    @ Gottadoit.........yup, RPCs is what i was concerned with
    Thanks all for getting back :)
     
  11. gottadoit

    gottadoit Security Expert

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  12. Rainwalker

    Rainwalker Registered Member

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  13. lotuseclat79

    lotuseclat79 Registered Member

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    Hi gottadoit,

    My point was that it was entirely possible to turn off RPC, and asserting that RPC "could possibly" be turned off only muddies one's understanding. What one needs to understand is what services are impacted when RPC is turned off, so the services that depend upon RPC are either disabled or scaled down in their capabilities, i.e. deprecated, or need to be started manually to reacquire other functionality. For example, although I run with RPC automatically started, I set to manual the other services needed for Windows Update and manually start those services every month for the updates from MS - not a good example to support my assertion below.

    My assertion is that it is entirely possible to run Windows without RPC, although at somewhat of a deprecated level as far as services are concerned.

    For example, the following services dependent on RPC are running automatically on my WinXP Pro SP2 system, while the remaining services that depend on RPC are either disabled or set to manual in my configuration:
    COM + Event System
    Crypotgraphic Services
    Error Reporting Service
    Fax
    Help and Support
    Logical Disk Manager
    Network Connections
    Print Spooler
    Protected Storage
    Security Accounts Manager
    Security Center
    System Restore Service
    Task Scheduler
    Windows Audio
    Windows Management Instrumentation
    Windows User Mode Driver Framework

    Note: this list is 16 in number as opposed to 43 system level services in total for Windows XP Pro SP2 depending on RPC - i.e. not counting 3rd party system level services which with RPC (not started) would probably prevent them from working as advertised.

    That said, Windows can work at a deprecated level, you just may not be able to do everything you want to do.

    -- Tom
     
  14. nick s

    nick s Registered Member

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