From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261710AbVGKOMS (ORCPT ); Mon, 11 Jul 2005 10:12:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261715AbVGKOKT (ORCPT ); Mon, 11 Jul 2005 10:10:19 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:62100 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S261710AbVGKOJS (ORCPT ); Mon, 11 Jul 2005 10:09:18 -0400 Subject: Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt From: Arjan van de Ven To: "Theodore Ts'o" Cc: Alan Cox , Lee Revell , Andrew Morton , azarah@nosferatu.za.org, cw@f00f.org, Linux Kernel Mailing List , torvalds@osdl.org, christoph@lameter.org In-Reply-To: <20050711140510.GB14529@thunk.org> References: <200506231828.j5NISlCe020350@hera.kernel.org> <20050708214908.GA31225@taniwha.stupidest.org> <20050708145953.0b2d8030.akpm@osdl.org> <1120928891.17184.10.camel@lycan.lan> <1120932991.6488.64.camel@mindpipe> <1120933916.3176.57.camel@laptopd505.fenrus.org> <1120934163.6488.72.camel@mindpipe> <20050709121212.7539a048.akpm@osdl.org> <1120936561.6488.84.camel@mindpipe> <1121088186.7407.61.camel@localhost.localdomain> <20050711140510.GB14529@thunk.org> Content-Type: text/plain Date: Mon, 11 Jul 2005 16:08:59 +0200 Message-Id: <1121090939.3177.30.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.2 (2.2.2-5) Content-Transfer-Encoding: 7bit X-Spam-Score: 2.9 (++) X-Spam-Report: SpamAssassin version 3.0.4 on pentafluge.infradead.org summary: Content analysis details: (2.9 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.1 RCVD_IN_SORBS_DUL RBL: SORBS: sent directly from dynamic IP address [80.57.133.107 listed in dnsbl.sorbs.net] 2.8 RCVD_IN_DSBL RBL: Received via a relay in list.dsbl.org [] X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > The real answer here is for the tickless patches to cleaned up to the > point where they can be merged, and then we won't waste battery power > entering the timer interrupt in the first place. :-) one big step forward for that is to have a mod_timer_relative() and add_timer_relative() which 1) take a relative delay as argument (and thus kill 99% of the jiffies use in the kernel right there and then) 2) takes it in miliseconds, killing 99% of all the HZ conversions/uses 3) takes a "accuracy" argument 3) is tricky I guess, it's designed for cases that are like "I want a timer 1 second from now, but it's ok to be also at 1.5 seconds if that suits you better". Those cases are far less rare than you might think at first, most watchdog kind things are of this type. This accuracy thing will allow the kernel to save many wakeups by grouping them I suspect. Alan: you worked on this before, where did you end up with ?