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Date:      Thu, 04 Dec 1997 12:10:47 -0700
From:      Steve Passe <smp@csn.net>
To:        Philippe Regnauld <regnauld@deepo.prosa.dk>
Cc:        dg@root.com, FreeBSD-current@FreeBSD.ORG
Subject:   Re: 3.0 -release ? 
Message-ID:  <199712041910.MAA13997@Ilsa.StevesCafe.com>
In-Reply-To: Your message of "Thu, 04 Dec 1997 12:34:19 %2B0100." <19971204123419.09270@deepo.prosa.dk> 

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Hi,

> 	My _personal_ opinion is that merging SMP into -current had one
> 	inevitable side-effect that maybe not many people thought about:
> 
> 	SMP is one _BIG_ lump to digest, and since it's not likely
> 	to be "retro-fitted" in -stable (unless many little green men
> 	come and help -- and maintain it after), it becomes the biggest
> 	single step to get over to reach the next release bump.
> 
> 	In a way, merging SMP has had a braking effect on release speed,
> 	but has not slowed down development in other places.
> 
> 	3.0 will be one _hell_ of a milestone.

Very well stated.  My "best wild guess" about SMP is that there is at least
6-9 person-months of work (probably more) before we meet David's benchmark:

>There are two things
>that need to be done: locks need to be pushed down so that we have at
>least per-subsystem locking (networking, filesystems, VM system, etc),
>and we need to rewrite the scheduler for process affinity.

I am in agreement with this target, but given the current level of work,
this will occur about 2-3 years from now!  We need more people actually
willing to do some coding and/or testing.

I have come to the conclusion (from (non)working experiments)  that some 
fundimental changes will need to be made to the kernel, primarily tossing
the spl mechanisms and using mutexs.  I am trying to get a serious design
discussion on SMP going in smp@freebsd.org, anyone is encouraged to join
us there if they wish to participate.

Although somewhat stale, there are many useful links to whitepapers
on SMP in:

http://www.freebsd.org/~fsmp/SMP/SMP.html


--
Steve Passe	| powered by 
smp@csn.net	|            Symmetric MultiProcessor FreeBSD





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