[SunRescue] OT: dual PPro mb's...

[Greg A. Woods]

[ On Thursday, March 29, 2001 at 21:26:34 (-0800), Cyrus M. Reed wrote: ]
> Subject: Re: [SunRescue] OT: dual PPro mb's...
>
> Don't forget that the cache runs at the full speed of the processor, not
> half like the PII chips.  I'm running a dual PPro 200 system as my main
> home desktop (which I've done for almost 3 years now), and it
> "feels" faster than the PII 450 machine I have access to at school.  Of
> course those run NT, and mine runs Linux...  That said, sounds like I
> should consider upgrading to the 2.4 kernel, so it can be even better. :)

Although running the cache at full speed is highly desirable, so is
having at least 512KB or more....  :-)

Rumour has it (I'm not a Linux user) even the 2.4 kernel has far
"grainier" data structure locking for SMP than would be desirable for
really good CPU utilisation.  I'm not sure how many CPUs it's designed
to handle well either.  IIRC Linus said something about the locking
being a little more coarse than he'd like in his rushed announcement of
the 2.4 kernel.

(I really don't know what the problem is -- the Bell Labs folks did a
dual-CPU implementation of V7 way back in the early 80's and there have
been lots of people doing it even better ever since and many of them
have documented their methods and the various tricks and traps they've
encountered along the way.  I.e. the knowledge is out there and it
should be trivial enough to apply it, especially in Linux where the main
target still seems to be the Intel processor family.  It should merely
be a matter of engineering at this point.  The NetBSD folks have been
doing a "clean" implementation and it'll probably pull up into the
public source in the next few months, and it's supposed to have fully
N-way CPU support and completely hardware independent.  I'll bet it gets
fine-grained locking far more quickly once it's public than any of the
other systems have apparently been managing.  That said though I've
heard very promising things from the FreeBSD folks, especially ever
since they joined forces with BSDi.)

-- 
							Greg A. Woods

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