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To: Scott Long <scottl@samsco.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Sun, 30 Jan 2005 23:49:43 MST."
             <41FDD507.2040409@samsco.org> 
Date: Mon, 31 Jan 2005 08:57:27 +0100
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cc: Mike Silbersack <silby@silby.com>
cc: Robert Watson <rwatson@freebsd.org>
cc: current@freebsd.org
cc: Colin Percival <cperciva@freebsd.org>
Subject: Re: tcp_isn_tick() / dummynet() callout madness ? 
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In message <41FDD507.2040409@samsco.org>, Scott Long writes:

>Taskqueues really are very non-deterministic and a poor choice for
>periodic events.  They really are only suitable for events that are
>uncommon and don't require any sense whatsoever of urgency.  While the
>callout API doesn't have any real-time guarantees, there is an
>assumption that assigned callouts will be generated with a reasonable
>amount of accuracy and consistency, and not be held up by a task that
>has an indefinite run time.  Either a new dedicated kthread-based task
>needs to be created for what you propose, or the simplier approach can
>be taken of just deferring callouts that fail the trylock test to the
>end of the list.

Either of those would work for me.

-- 
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.