Windows 2000 Debugger

OSR_Community_User · November 9, 2000, 1:58pm

I am currently looking in to a potential issue with a USB device driver I
wrote for Windows 2000. My question is not related to the driver issue, but
rather the Windows debugger.

The driver processes Video Frames from a camera, and displays them on the
host. I usually get a frame rate of about 11 FPS.

When I boot 2000 into Debug mode, thus starting the Kernel debugger I get
about 1 Frame every 3 Seconds. When I do some profiling of the system using
Task Manager|Performace Tab, it shows the CPU being Pegged %100 (With a
very large amount of the time being spend in the kernel (RED)).

Anyone know what could be causing this, how does the Kernel Debugger
interact with the OS. I would expect slower performance when using the
kernel debugger, but not that slow.

Any data regarding how the Kernel debugger interfaces with the OS would be
greatly appreciated.

Thanks

-Chris

Christopher Pane
Software Engineer
Vanteon

2851 Clover Street
Pittsford, NY 14534
Tel: (716) 248-0510 (Ext 232)
Fax: (716) 248-0537

email: xxxxx@vanteon.com
web: www.vanteon.com

OSR_Community_User-48 · November 9, 2000, 2:39pm

Adding the debugger will add overhead, of course. There are somethings
you can do to help make sure it’s impact is minimal.

Here are 2 obivous things that come to mind to help speed up system
performance while connected to the debugger.

Use the debugger at the highest baud rate (115200 baud). As
the whole system freezes when packets are being sent, this will help
keep the time to send the packets down as low as they can go. See the
debugger docs on how to change this.
Don’t cause unnessacry packets to be. One good example is
debug print statements. The whole machine stops when this is being
sent. Only send the spew you are really interested in. I’ve heard of
some people implemented a circular message buffer in thier driver and
print to that. Then when a failure occurs they use a debugger extension
to dump the last x messages. Using something like that would help
minimize debugger spew & still have the info when needed.

Hope that helps

-----Original Message-----
From: Pane, Chris [mailto:xxxxx@vanteon.com]
Sent: Thursday, November 09, 2000 10:54 AM
To: NT Developers Interest List
Subject: [ntdev] Windows 2000 Debugger

I am currently looking in to a potential issue with a USB device driver
I
wrote for Windows 2000. My question is not related to the driver issue,
but
rather the Windows debugger.

The driver processes Video Frames from a camera, and displays them on
the
host. I usually get a frame rate of about 11 FPS.

When I boot 2000 into Debug mode, thus starting the Kernel debugger I
get
about 1 Frame every 3 Seconds. When I do some profiling of the system
using
Task Manager|Performace Tab, it shows the CPU being Pegged %100 (With a
very large amount of the time being spend in the kernel (RED)).