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Date:      Mon, 7 Oct 2002 13:39:13 -0400 (EDT)
From:      Gary Thorpe <gathorpe79@yahoo.com>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        freebsd-arch@freebsd.org
Subject:   Re: Running independent kernel instances on dual-Xeon/E7500 system
Message-ID:  <20021007173913.50425.qmail@web11207.mail.yahoo.com>
In-Reply-To: <3DA10949.218488B9@mindspring.com>

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--- Terry Lambert <tlambert2@mindspring.com> wrote:
> Nate Lawson wrote:
> > My dismissiveness was due to anticipating the
> direction this was going,
> > which is nicely shown by the response below.  In
> short, dedicated
> > processors for IO were used in the minicomputer
> days but are wasteful
> > nowadays when you have lightweight interrupts
> and/or polling when
> > appropriate.
> 
> Yet, I keep running into employers who want to pay
> people to do
> exactly that, particularly for offloading network
> processing to
> one processor, and running applications on the
> other.

Wouldn't this be "solved" by using thread affinity?

> 
> And then there's the Tigon II firmware rewrite for
> FreeBSD, to
> offload interrupt and copy processing.  And CGD's
> work for Sibytes
> (NetBSD 64bit MIPS-based network coprocessor board)
> doing just that
> got the company sold to Broadcom for what, $700M?
> 
> 8-).
> 
> 
> > If your scheduler sucks, fix it.  If a device
> needs extra processing
> > equivalent to another N Ghz CPU, the vendor will
> add silicon.  The "S" in
> > SMP is for symmetric, lest we forget.
> 
> People keep saying that, and then keep not running
> interrupts in
> virtual wire mode, so that their delivery is "S" as
> in "symmetric"...
> ;^).
> 
> Actually, NT proved that wiring particular
> interrupts to particular
> processors was the way to go -- that was one of the
> things they did
> to beat the Linux numbers in both the Netcraft and
> Ziff-Davis
> benchmarks... perfect symmetry isn't all that it's
> promised.
> 
> -- Terry

I remember when I mentioned that some time ago and got
the general response that this setup is highly
specialized, inflexible, and probably not very useful
for a real-world server. People did point of that with
MORE cpus and/or MORE network adapters or some
combinations that is not n:n ratio, NT would not have
scaled well at all. How would NT compare to Tru64,
Solaris, AIX, or IRIX in a similar test? Do any of
these "hardwire" interrupts to particular cpus?

I think what the original poster would want is
something like user-mode linux or vmware. Aside from
machine emulation (via bochs and simular simulators),
does anything exist for FreeBSD which would allow you
to run seperate, independent environments?


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