From owner-freebsd-hackers Tue Feb 5 9:10:45 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by hub.freebsd.org (Postfix) with ESMTP id 67E6A37B419; Tue, 5 Feb 2002 09:10:40 -0800 (PST) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.11.6/8.11.6) with ESMTP id g15H7YM90117; Tue, 5 Feb 2002 18:07:34 +0100 (CET) (envelope-from phk@critter.freebsd.dk) To: John Polstra Cc: hackers@FreeBSD.ORG, jhb@FreeBSD.ORG Subject: Re: A question about timecounters In-Reply-To: Your message of "Tue, 05 Feb 2002 09:06:51 PST." <200202051706.g15H6pp03714@vashon.polstra.com> Date: Tue, 05 Feb 2002 18:07:34 +0100 Message-ID: <90115.1012928854@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In message <200202051706.g15H6pp03714@vashon.polstra.com>, John Polstra writes: >In article , >John Baldwin wrote: >> >> > like, "If X is never locked out for longer than Y, this problem >> > cannot happen." I'm looking for definitions of X and Y. X might be >> > hardclock() or softclock() or non-interrupt kernel processing. Y >> > would be some measure of time, probably a function of HZ and/or the >> > timecounter frequency. >> >> X is hardclock I think, since hardclock() calls tc_windup(). > >That makes sense, but on the other hand hardclock seems unlikely to be >delayed by much. The only thing that can block hardclock is another >hardclock, an splclock, or an splhigh. And, maybe, splstatclock. I'm >talking about -stable here, which is where I'm doing my experiments. Try swapping so you use the RTC for hardclock & statclock. Let the i8254 run with 65536 divisor and do only timecounter service. That would be a very interresting experiment. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message