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Date:      Sun, 26 Mar 2000 13:37:50 +0100 (BST)
From:      Doug Rabson <dfr@nlsystems.com>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Alfred Perlstein <bright@wintelcom.net>, freebsd-current@freebsd.org
Subject:   Re: SMP/BGL patch 04
Message-ID:  <Pine.BSF.4.21.0003261333440.89245-100000@salmon.nlsystems.com>
In-Reply-To: <200003250216.SAA18264@apollo.backplane.com>

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On Fri, 24 Mar 2000, Matthew Dillon wrote:

>     Patch 04 is ready.
> 
>     http://www.backplane.com/FreeBSD4/
>     http://www.backplane.com/FreeBSD4/smp-patch-04.diff
> 
>     Contains lots of cleanup of stale SMP code.  There are still a few places
>     where get_mplock is being called with interrupts disabled which I haven't
>     found, so I put the sti test back in.
> 
>     I also removed the FAST_SIMPLELOCK optimization, which had been turned
>     on - mainly because it's not useful if we are moving to an interrupt 
>     thread scheme (as in it's still a global interrupt lock, whereas the
>     thread scheme will allow concurrent interrupt execution), but also 
>     because it makes too many assumptions about what can run outside the 
>     MP lock.
> 
>     I'm going to let people bang on this for a few days, and then I think
>     it should be committed into -CURRENT (5.x) in order to allow people
>     to start banging on optimizing the BGL/syscall paths.  All comments
>     welcome (but not necessary acted upon) :-).

I haven't looked at the patch so I can't comment on it (but it sounds very
promising).

I have been writing some of the infrastructure for SMP on alpha and as an
experiment I've been using the mutex_t primitive from BSD/OS as an
experiment. This is a nice simple api for a counting mutex which BSD/OS
4.1 uses for its BGL. I have not yet seen the new BSD/OS smp code but it
seemed that using mutex_t might make it marginally easier to work with
that.

--
Doug Rabson				Mail:  dfr@nlsystems.com
Nonlinear Systems Ltd.			Phone: +44 181 442 9037




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