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Date:      Wed, 22 Mar 2000 17:58:58 -0800
From:      "Jeremiah Gowdy" <jgowdy@home.com>
To:        "James" <jkelty@digital-impact.com>, <freebsd-questions@FreeBSD.ORG>
Subject:   Re: SMP specifics.......?????????
Message-ID:  <000f01bf946b$5ae2fca0$0100000a@vista1.sdca.home.com>
References:  <CPEEKAEIEILAHOOFPBOICEDCCDAA.jkelty@digital-impact.com>

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> Does the SMP support allow a process running on each CPU to talk to a
single
> device with locking the kernel up?

It should act the same way as if two processes accessed the device at the
same time.  Shouldn't lock anything up.

>Is it true SMP, or just a little more
> processing power?

How could it not be true SMP ?  What would qualify as just a little more
processing power ?

The only way I could see it being implemented, on any system, not just
FreeBSD, is that the task scheduler runs two processes at once, one on each
processor.  That's the only way a second processor would add any more
processing power.  A priority queue with two places for output/processing
rather than one.  I can't really think of a cheezy way to do it that
wouldn't qualify as SMP.  Now, I know SMP has other features, like processor
affinity and whatnot, of which I'm not familiar, which would be a better
implementation.  However, even the crappiest implementation of SMP is still
"true SMP".

As for FreeBSD's SMP, I've not seen any specifics on the implemenatation,
except that I hear 4.0 includes linux/processor threads, which allows a
multithreaded program's threads to use either processor, allowing a single
highly active multithreaded process to use the SMP setup.





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