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Subject: Re: No 100 HZ timer !
To: mikulas@artax.karlin.mff.cuni.cz (Mikulas Patocka)
Date: Mon, 9 Apr 2001 23:35:44 +0100 (BST)
Cc: alan@lxorguk.ukuu.org.uk (Alan Cox), mbs@mc.com (Mark Salisbury),
        jdike@karaya.com (Jeff Dike), schwidefsky@de.ibm.com,
        linux-kernel@vger.kernel.org
In-Reply-To: <Pine.LNX.3.96.1010410002852.4212A-100000@artax.karlin.mff.cuni.cz> from "Mikulas Patocka" at Apr 10, 2001 12:31:08 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> > Its worth doing even on the ancient x86 boards with the PIT.
> 
> Note that programming the PIT is sloooooooow and doing it on every timer
> add_timer/del_timer would be a pain.

You only have to do it occasionally.

When you add a timer newer than the current one 
	(arguably newer by at least 1/2*HZ sec)
When you finish running the timers at an interval and the new interval is
significantly larger than the current one.

Remember each tick we poke the PIT anyway

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