Message-ID: <17594.192.54.193.25.1134477932.squirrel@rousalka.dyndns.org>
Date: Tue, 13 Dec 2005 13:45:32 +0100 (CET)
Subject: Re: [patch 00/21] hrtimer - High-resolution timer subsystem
From: "Nicolas Mailhot" <nicolas.mailhot@laposte.net>
To: "Thomas Gleixner" <tglx@linutronix.de>
Cc: "Roman Zippel" <zippel@linux-m68k.org>, linux-kernel@vger.kernel.org
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"This is your interpretation and I disagree.

If I set up a timer with a 24 hour interval, which should go off
everyday at 6:00 AM, then I expect that this timer does this even when
the clock is set e.g. by daylight saving. I think, that this is a
completely valid interpretation and makes a lot of sense from a
practical point of view. The existing implementation does it that way
already, so why do we want to change this ?"

Please do not hardcode anywhere 1 day = 24h or something like this.
Relative timers should stay relative not depend on DST.

If someone needs a timer that sets of everyday at the same (legal) time,
make him ask for everyday at that time not one time + n x 24h.

Some processes need an exact legal hour
Other processes need an exact duration

In a DST world that's not the same thing at all - don't assume one or the
other, have coders request exactly what they need and everyone will be
happy.

I can tell from experience trying to fix code which assumed one day = 24h
is not fun at all. And yes sometimes the difference between legal and UTC
time matters a lot.

-- 
Nicolas Mailhot

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