Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 18 Feb 2002 19:19:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 18 Feb 2002 19:19:16 -0500 Received: from tmr-02.dsl.thebiz.net ([216.238.38.204]:65291 "EHLO gatekeeper.tmr.com") by vger.kernel.org with ESMTP id ; Mon, 18 Feb 2002 19:19:11 -0500 Date: Mon, 18 Feb 2002 19:17:33 -0500 (EST) From: Bill Davidsen To: Ben Greear cc: Linux Kernel Mailing List Subject: Re: jiffies rollover, uptime etc. In-Reply-To: <3C717DEA.7090309@candelatech.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 18 Feb 2002, Ben Greear wrote: > I wonder, is it more expensive to write all drivers to handle the > wraps than to take the long long increment hit? The increment is > once every 10 miliseconds, right? That is not too often, all things > considered... If you are willing to code in assembler instead of C you can do better, at least on x86. You just need to do a 32 bit increment on the LS word, and if you get a carry you can incr the MS word. > Maybe the non-atomicity of the long long increment is the problem? I doubt it, the problem is that the software which expects jiffies is not all going to work well 64 bit. I think that's more the issue, and why Alan et al are fixing it piecemeal, I don't think there's some magic fix they're missing. > Does this problem still exist on 64-bit machines? Absolutely. But not as often ;-) -- bill davidsen CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/