DPC latency

xxxxx@attotech.com wrote:

I’ve recently run across a system (dual Itanium) where the average DPC
latency was very low (<1 ms), but occassionally (once a second or so)
would be 15-20 ms. I assumed some other device on the system was
taking a long time in an ISR or DPC and causing the delay.

The RealTek audio driver on the Intel 915 motherboard I have as a test
machine had a nasty habit of running KeStallExecutionProcessor with a
parameter of 10,000. Those of you keeping score at home will recognize
that this does a tight kernel-mode loop for 10 milliseconds.

I couldn’t figure out why one of the CPUs on my Hyperthreaded P4 2.8GHz
was always 35% loaded. That was why.