From owner-freebsd-hackers Tue Feb 5 10:52:32 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from ns.yogotech.com (ns.yogotech.com [206.127.123.66]) by hub.freebsd.org (Postfix) with ESMTP id A8B4637B41B for ; Tue, 5 Feb 2002 10:52:22 -0800 (PST) Received: from caddis.yogotech.com (caddis.yogotech.com [206.127.123.130]) by ns.yogotech.com (8.9.3/8.9.3) with ESMTP id LAA03723; Tue, 5 Feb 2002 11:51:58 -0700 (MST) (envelope-from nate@yogotech.com) Received: (from nate@localhost) by caddis.yogotech.com (8.11.6/8.11.6) id g15Ipw568733; Tue, 5 Feb 2002 11:51:58 -0700 (MST) (envelope-from nate) From: Nate Williams MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15456.10702.319710.952387@caddis.yogotech.com> Date: Tue, 5 Feb 2002 11:51:58 -0700 To: Poul-Henning Kamp Cc: John Polstra , hackers@FreeBSD.ORG Subject: Re: A question about timecounters In-Reply-To: <91325.1012934584@critter.freebsd.dk> References: <200202051826.g15IQDt04095@vashon.polstra.com> <91325.1012934584@critter.freebsd.dk> X-Mailer: VM 6.96 under 21.1 (patch 14) "Cuyahoga Valley" XEmacs Lucid Reply-To: nate@yogotech.com (Nate Williams) 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 > >> Can you try to MFC rev 1.111 and see if that changes anything ? > > > >That produced some interesting results. I am still testing under > >very heavy network interrupt load. With the change from 1.111, I > >still get the microuptime messages about as often. But look how > >much larger the reported backwards jumps are: > > > > microuptime() went backwards (896.225603 -> 888.463636) > > microuptime() went backwards (896.225603 -> 888.494440) > > microuptime() went backwards (896.225603 -> 888.500875) > > microuptime() went backwards (1184.392277 -> 1176.603001) > > microuptime() went backwards (1184.392277 -> 1176.603749) > > (Ok, I'll MFC 1.111) Huh? It appears that 1.111 makes things worse, not better (larger jumps). Can you explain why you think this is a good things, since it seems to be a bad thing to me. > Sanity-check: this is NOT a multi-CPU system, right ? As stated before, both are > 1Ghz single-CPU systems running -stable, although I'm sure John is capable of a answering this on his own. :) > We now have three options left: > hardclock interrupt starvation This is Bruce's hypothesis, right? > scheduling related anomaly wrt to the use of microuptime(). > arithmetic overflow because the call to microuptime() gets > interrupted for too long. 'Interrupted for too long'. Do you mean 'not interrupted enough', aka a long interrupt blockage? (I'm trying to understand here.) Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message