[Winpcap-users] Re: SMP support not working?

Noam Dev noamdev at gmail.com
Thu Mar 1 17:46:20 GMT 2007

>From process explorer, the CPU Usage stats look like this :
10-13% Interrupts
10-13% DPCs (Deferred procedure calls i believe)

The windump processes themselves take close to no cpu...

 ----- Original Message -----
From: "Gianluca Varenni" <gianluca.varenni at cacetech.com>
Subject: Re: [Winpcap-users] SMP support not working?
To: <winpcap-users at winpcap.org>
Message-ID: <0d1401c75ae6$29f50590$1a4da8c0 at NELSON2>
Content-Type: text/plain; charset="iso-8859-1"

 ----- Original Message -----
 From: Noam Dev
 To: winpcap-users
 Sent: Tuesday, February 27, 2007 1:55 PM
 Subject: [Winpcap-users] SMP support not working?


 I am running winpcap 3.1 (haven't moved to 4.0 yet) on a windows 2003
 The server has 4 processors. When i run multiple instances of windump (just
one network card),
 they all run on the first processor. I can see that because when i load
 and run many instances of windump, the cpu usage stats of the computer rise
 25%, with the first cpu being almost fully-used all of the time and the
rest being idle.

 I see that winpcap should have SMP support. Am I doing anything wrong?

Uhm, I think there is a bit of confusion here as to what SMP support means.
If you have 4 CPUs and 4 instances of windump, it's up to the OS scheduler
to decide where each process will run, and this changes from time to time.
Moreover WinPcap is a user level library (some DLLs) and a driver (npf.sys).
The user level libraries "run" on the CPU the process calling them is
running on. For the driver it's a bit more complicated, but the idea is
somewhat similar. At the end of the story the driver is a set of functions
that the OS calls to delivers packets to user level. Again it's the OS that
usually decides which CPU the various driver functions will run on (this is
an OVERSIMPLIFICATION, driver devs please don't yell at me).

You are saying that one CPU is almost 100% loaded and the other ones idle.
What is the CPU load of each of the instances of windump.exe that are

Hope it helps
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