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Date: Tue, 18 Apr 1995 18:40:44 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199504180840.SAA13096@godzilla.zeta.org.au>
To: chitra@CS.SunySB.EDU, freebsd-hackers@FreeBSD.org
Subject: Re: help with timeouts
Sender: hackers-owner@FreeBSD.org
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>I am developing a token bus protocol in the FreeBSD network
>interrupt handler. For the
>token recovery algorithm that I have, I need to set microsecond
>timeouts (they could be off by upto 500 u_sec and still serve my purpose).
>As things are now, I can only set timeouts in multiples of 10 millisec.
>Can you please tell me how I can implement u_sec timeouts ?

acquire_timer0(your_interrupt_rate, your_interrupt_handler) is suitable
for high frequency periodic timeouts (preferably a multiple of 100 Hz), 
but only works if another driver hasn't already `acquired' the timer.
acquire_timer0() was nontrivial to implement (see clkintr() in clock.c)
and a general aperiodic timer would be harder.

Bruce