Date: Mon, 16 Sep 2002 22:17:55 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Harti Brandt <brandt@fokus.gmd.de> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, Josef Karthauser <joe@FreeBSD.ORG>, "David O'Brien" <obrien@FreeBSD.ORG>, <cvs-committers@FreeBSD.ORG>, <cvs-all@FreeBSD.ORG> Subject: Re: cvs commit: src/sys/kern kern_timeout.c Message-ID: <20020916220519.V6839-100000@gamplex.bde.org> In-Reply-To: <20020916123330.R92332-100000@beagle.fokus.gmd.de>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, 16 Sep 2002, Harti Brandt wrote:
> On Mon, 16 Sep 2002, Poul-Henning Kamp wrote:
> PK>I have a point on my TODO list about improving DELAY(), but nobody
> PK>has picked it up yet.
DELAY() should use a calibrated spinloop for small delays and when
nanouptime() is not available, and nanouptime() combined with
recalibrating the loop otherwise. Note that nanotime() is not available
(a) before timecounters are initialized
(b) when clocks are stopped, perhaps by ddb
(c) when the hardware being nanotime() is locked, perhaps because DELAY()
is being called from the keyboard driver from inside ddb after ddb
has stopped the system at a breakpoint while the hardware is locked.
> Well, Mike Silbersack has pointed me to that TODO entry. Although I have
> an oscilloscope and a couple of different machines, its a matter of time.
> Its also not a matter of indirecting the DELAY() function to one or two
> function pointers - when I used the 'correct' DELAY for the entire xl
> driver it failed to attach. The problem is that a number of DELAY(1) calls
> assume that the delay is actually larger (see also the hackers discussion
> in january) - one would need to go through all DELAY() calls with small
> values and check what they are really used for.
I hope that is FUD. We went through all the drivers about 7 years ago, and
new drivers wouldn't repeat this mistake :-).
Bruce
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe cvs-all" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20020916220519.V6839-100000>