From: Mark Roddy [markr@hollistech.com]
Sent: Saturday, January 27, 2001 8:34 AM
To: NT Developers Interest List
Subject: [ntdev] RE: DPC question

Your ISR runs at DIRQL  (some IRQL level > DISPATCH_LEVEL and less than PROFILE_LEVEL.) When you queue a DPC from an ISR you are essentially requesting that your DPC function be called when the target processor transitions from > DISPATCH_LEVEL to < DISPATCH_LEVEL. This transition triggers DPC queue processing at DISPATCH_LEVEL before the transition is completed. 
 
 
Mark Roddy
Windows 2000/NT Consultant
Hollis Technology Solutions
www.hollistech.com 

    -----Original Message-----
    From: bounce-ntdev-311@lists.osr.com [mailto:bounce-ntdev-311@lists.osr.com]On Behalf Of Matteo Pelati
    Sent: Saturday, January 27, 2001 7:41 AM
    To: NT Developers Interest List
    Subject: [ntdev] DPC question
    
    
    It's a bit unclear to me when exactly a DPC is invoked by the I/O Manager. Supposing I'm executing an ISR and i call the IoRequestDpc() function a new DPC object will be inserted in the system's DPC queue. Now, I suppose the system will continue executing the ISR (at DISPATCH_LEVEL) and my DPC is ready to be executed. 
     
    When exactly this will be execued ? As I complete my ISR (that means when the system goes back to PASSIVE_LEVEL) ? So, what triggers the execution of the DPC ?
    
    Thanks
    Matteo 
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