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To: Ian Dowse <iedowse@maths.tcd.ie>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 17 Nov 2004 23:22:56 GMT."
             <200411172322.aa34520@salmon.maths.tcd.ie> 
Date: Tue, 30 Nov 2004 17:34:45 +0100
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Sender: phk@critter.freebsd.dk
cc: arch@freebsd.org
Subject: Re: Simpler SMP-friendly callout/timeout semantics 
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In message <200411172322.aa34520@salmon.maths.tcd.ie>, Ian Dowse writes:
>
>The current callout/timeout API supports Giant-locked and MP-safe
>usage options, but in both cases it is very difficult to use the
>API in a way that is free of race conditions and complications.
>Below is an attempt to extend that API to offer much simpler semantics
>to many users while not limiting its usefulness or performance.
>
>Do people think that a change like this is worth attempting? Are
>there further improvements that could be made or any other suggestions
>or comments?

Sounds good to me.

Do you try to optimize softclock to not stall on the mutex and instead
find any other pending callouts to handle ?

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.