[WinMac] Re: dual processors on NT Servers

Daniel L. Schwartz(expresso[at]snip.net)
Tue, 05 Oct 1999 15:06:44 -0400

        Yes, NT is, and always has been. a fully symmetrical multiprocessor
operating system. Unlike MacOS & NetWare, which are pretty much
asymmetrical, NT's thread scheduler will gladly dispatch tasks to the
available CPU's by which one has the lightest load.

        BTW, along these same lines, this was one of the reasons that NT blew
linux out of the water in the controversial NT-linux shootout in early
summer: The testbed was a 4 CPU Dell box with 4GB of RAM. When the second
round of tests were performed - With RedHat & Microsoft engineers each
optimizing their respective systems - it was discovered that linux didn't
have a multithreaded TCP/IP stack!

 ------

        Just imagine the (hypothetical) men's room conversation at the lab:

        "Let's see, we don't have a multithreaded IP stack. Let's throw this into
the kernel and recompile..."

        "What about regression testing for quality & compatibility before putting
this out there?"

        "Ha Ha! This is Linux - As long as it works on this machine, fine.
Everyone else'll have to edit the kernel to suit their own "needs:" This is
"open source" at it's finest!"

 ------

        Going back to the original NT question, applications don't need to know
anything about the hardware: They are "cradled" by the HAL (Hardware
Abstraction Layer) of NT, and NT will "break up" the application into its'
DLL (Dynamic Link Library) threads and distribute the threads amongst the
CPU's.

        [Note that there *is* an exception: old 16 bit apps, which are run in
NTVDM (NT Virtual DOS Machine, an x86 emulator): Normally, NTVDM's run in
their own separate processes; but there are a few cases where the
"DefaultSeparateNTVDM" key has to be set to "No" in order for multiple
legacy apps to communicate between each other. In this case, NTVDM.EXE will
also run on only a single CPU. The obvious answer is to get rid of as much
of the 16 bit crap as possible: On a well-oiled NT Server this shouldn't be
too difficult]

        A good source of NT reference material is Sean Daily's "Optimizing Windows
NT" (IDG Books, ISBN 0-7645-3110-7): It's about $39 or so from the online
book stores (amazon, etc...).

        Hope this helps!
        Dan

At 01:45 PM 10/5/99 -0400, you wrote:
>
>With all the talk about servers these past few days I thought I'd ask a
>question that I've been thinking about for some time now. Just how much
>advantage is there using dual processors on an NT Server? Does the NT
>operating system really take advantage of the two processors? Is that
>extra processing power then available to just any program or they have
>to be specifically written to use two processors? I've got a dual
>300Mhz Dell PowerEdge 4200 running NT Server with 256MB of RAM.
>
> ______________________________________________________________________
> Tom Roth Wake Forest University School of Medicine
> tomroth@wfubmc.edu Dept of Biomedical Communications
> http://www.wfubmc.edu/biomed/ Medical Center Blvd
> Tel 336.716.4493 Winston-Salem, NC 27157-1011
> ______________________________________________________________________

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