Deferred procedure call

[leechat2001]

1. What is a deferred procedure call?
2. What is the difference between IRP and IRQL?


Please help..!

thanks
leechat2001

 

[lambtron]

What is a deferred procedure call?

A DPC is code that executes in response to an interrupt, but the function it performs does not have such high priority that it must execute within the interrupt handler.

For example, suppose an ethernet packet was just received. An isr must immediately remove the packet from the ethernet interface and put it into a memory buffer. After that, some further work must be done to process the packet, but this can be done sometime later at lower priority. So the isr, after saving the packet to memory, schedules deferred processing of the packet buffer. The actual "scheduling" of the dpc is typically implemented by posting a semaphore, queue, etc. to unblock a waiting dpc thread.