Hi,
did I got it right that I can change the parameter IdealDpcRate? How? Is
it located somewhere in registry? In which operating systems?
Thanx for your help!
Olav
Subject: Re: Re:DPC latency
From: “Maxim S. Shatskih”
Date: Wed, 30 Mar 2005 13:52:53 +0400
X-Message-Number: 8
> also see interrupt/DPC latency that is pretty horrendous because the IDE
> driver has to do the read-out from the hard-disk (or write-on to) in PIO
> mode, which will, if I remember correctly, be done in either the interrupt
> handler or a DPC.
In the ISR.
BTW - DPCs are not fired exactly on IRQL drop to < DISPATCH - this is true
only
on an idle CPU. Otherwise, they are sometimes delayed till the next timer
tick,
and the kernel parameter IdealDpcRate in the registry governs this. Try
playing
with it.
So, DPC latency can really be a timer tick even with a well-written driver.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com