From owner-freebsd-hackers Thu Jul 2 06:11:58 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id GAA17753 for freebsd-hackers-outgoing; Thu, 2 Jul 1998 06:11:58 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from oslo.geco-prakla.slb.com (geos01.oslo.geco-prakla.slb.com [134.32.44.131]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id GAA17735; Thu, 2 Jul 1998 06:11:47 -0700 (PDT) (envelope-from smoergrd@geos01.oslo.geco-prakla.slb.com) Received: from sunw132.geco-prakla.slb.com (sunw132 [134.32.45.120]) by oslo.geco-prakla.slb.com (8.8.8/8.6.9) with SMTP id PAA03241 ; Thu, 2 Jul 1998 15:11:14 +0200 (MET DST) Received: by sunw132.geco-prakla.slb.com (SMI-8.6/SMI-SVR4) id PAA08121; Thu, 2 Jul 1998 15:11:13 +0200 To: Luigi Rizzo Cc: sos@FreeBSD.ORG, nick.hibma@jrc.it, hackers@FreeBSD.ORG Subject: Re: timeout granularity (was: Re: Console driver...) References: <199807021127.NAA12406@labinfo.iet.unipi.it> Organization: Schlumberger Geco-Prakla X-Disclaimer: I speak only for myself. From: smoergrd@oslo.geco-prakla.slb.com (Dag-Erling Coidan Smørgrav) Date: 02 Jul 1998 15:11:13 +0200 In-Reply-To: Luigi Rizzo's message of Thu, 2 Jul 1998 13:26:59 +0200 (MET DST) Message-ID: Lines: 19 X-Mailer: Gnus v5.3/Emacs 19.34 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Luigi Rizzo writes: > [about default timer granularity being too coarse for sampling > the vertical retrace interval] > > the code might check if HZ is set to a suitable value (how large, > e.g. 1000 or 2000, i have no idea) and use timeout instead of > polling if the test is successful. Sooner or later hopefully we > will move to large values of HZ anyways. > > (or, how about adding a utimeout() call to the kernel :) It's not that simple. You have to know how long to wait, which is practically impossible to do without hooking the timer interrupt and reprogramming it to keep pace with the retrace, and even that is difficult to achieve without a little busy-waiting here and there. DES -- Dag-Erling Smørgrav - smoergrd@oslo.geco-prakla.slb.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message