From owner-freebsd-current Sat Feb 28 02:30:02 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id CAA21975 for freebsd-current-outgoing; Sat, 28 Feb 1998 02:30:02 -0800 (PST) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from ocean.campus.luth.se (ocean.campus.luth.se [130.240.194.116]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA21937 for ; Sat, 28 Feb 1998 02:29:57 -0800 (PST) (envelope-from karpen@ocean.campus.luth.se) Received: (from karpen@localhost) by ocean.campus.luth.se (8.8.8/8.8.8) id LAA04326; Sat, 28 Feb 1998 11:26:36 +0100 (CET) (envelope-from karpen) From: Mikael Karpberg Message-Id: <199802281026.LAA04326@ocean.campus.luth.se> Subject: Re: Curious: "Timecounter"? In-Reply-To: <3448.888596014@critter.freebsd.dk> from Poul-Henning Kamp at "Feb 27, 98 05:13:34 pm" To: phk@critter.freebsd.dk (Poul-Henning Kamp) Date: Sat, 28 Feb 1998 11:26:35 +0100 (CET) Cc: current@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL32 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG According to Poul-Henning Kamp: > In message <19980227095115.05314@urh.uiuc.edu>, dannyman writes: > >arh0300 kernel log messages: > >> Timecounter "i8254" frequency 1193182 Hz cost 2524 ns > >> Timecounter "TSC" frequency 99952423 Hz cost 356 ns [...] > It means that the machine has two pieces of hardware it can use for > the construction of "time-of-day". > > "frequency" should be pretty obvious, "cost" is how long time it takes > to read the counter, and consequently a measure of the overhead by using > that timecounter. Does the system pick the fastest one and use that? Does it use both? (Maybe to see if one of the sources is drifting, etc?) /Mikael To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message