From owner-freebsd-hackers Sat Nov 18 15:45:17 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id PAA25973 for hackers-outgoing; Sat, 18 Nov 1995 15:45:17 -0800 Received: from werple.net.au (0@werple.mira.net.au [203.9.190.18]) by freefall.freebsd.org (8.6.12/8.6.6) with ESMTP id PAA25956 for ; Sat, 18 Nov 1995 15:45:03 -0800 Received: from cimaxp1.UUCP (Ucimlogi@localhost) by werple.net.au (8.7/8.7.1) with UUCP id KAA09250 for hackers@FreeBSD.org; Sun, 19 Nov 1995 10:01:40 +1100 (EST) Message-Id: <199511182301.KAA09250@werple.net.au> X-Authentication-Warning: werple.net.au: Ucimlogi set sender to cimaxp1!jb using -f Received: by cimaxp1.cimlogic.com.au; (5.65/1.1.8.2/10Sep95-0953AM) id AA13997; Sun, 19 Nov 1995 10:05:40 +1100 From: John Birrell Subject: Re: DELAY's in syscons To: lambert.org!terry@werple.net.au (Terry Lambert) Date: Sun, 19 Nov 1995 10:05:39 +1100 (EST) Cc: hackers@FreeBSD.org, jb@cimlogic.com.au In-Reply-To: <199511182140.OAA09716@phaeton.artisoft.com> from "Terry Lambert" at Nov 18, 95 02:40:55 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-hackers@FreeBSD.org Precedence: bulk > > I think this only works reliably for 8MHz ISA buses. Otherwise I would > > have used it in DELAY(). The only way it can be reliable is if all buses > > know it is special and put something there that inserts wait states to > > extend the i/o time to 1.25us. > > Time to scream about high resoloution kernel timers once again? A nice > reschedulable one-shot HRT interface would fix DELAY right up. There > are only *minor* kernel preemption issues involved. What are the issues about getting better time resolution in general from the kernel? With process control software (that is threaded) running flat out in memory (no disk or network I/O), we notice the timer resolution. We'd also like a better nanosleep than we get using select. Is nanosleep something you'd implement with your "reschedulable one-shot HRT interface"? > > > Terry Lambert > terry@lambert.org > --- > Any opinions in this posting are my own and not those of my present > or previous employers. > -- John Birrell CIMlogic Pty Ltd jb@cimlogic.com.au 119 Cecil Street Ph +61 3 9690 9600 South Melbourne Vic 3205 Fax +61 3 9690 6650 Australia Mob +61 18 353 137