From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261465AbULNJiJ (ORCPT ); Tue, 14 Dec 2004 04:38:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261466AbULNJiJ (ORCPT ); Tue, 14 Dec 2004 04:38:09 -0500 Received: from gprs214-98.eurotel.cz ([160.218.214.98]:21376 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S261465AbULNJiE (ORCPT ); Tue, 14 Dec 2004 04:38:04 -0500 Date: Tue, 14 Dec 2004 10:37:35 +0100 From: Pavel Machek To: Tony Lindgren Cc: john stultz , Andrea Arcangeli , Zwane Mwaikambo , Con Kolivas , lkml Subject: Re: dynamic-hz Message-ID: <20041214093735.GA1063@elf.ucw.cz> References: <20041213002751.GP16322@dualathlon.random> <20041213112853.GS16322@dualathlon.random> <20041213124313.GB29426@atrey.karlin.mff.cuni.cz> <20041213125844.GY16322@dualathlon.random> <20041213191249.GB1052@elf.ucw.cz> <1102970039.1281.415.camel@cog.beaverton.ibm.com> <20041213204933.GA4693@elf.ucw.cz> <20041214013924.GB14617@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041214013924.GB14617@atomide.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.6+20040722i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > > > > But that does not matter, right? Yes, one-shot timer will not fire > > > > > > exactly at right place, but as long as you are reading TSC and basing > > > > > > next shot on current time, error should not accumulate. > > > > > > > > > > As said in the rest of the message, the error (or some other error) > > > > > accumulates heavily today in the tick-loss compensation/adjustment > > > > > algorithm in arch/i386/kernel/timers/timer_tsc.c, so I'm sceptical > > > > > about > > > > > > > > I do not see how it should accumulate. Lets have working TSC. You want > > > > to emulate fixed-period timer with single-shot timer. > > > > > > Its caused by the fact that we don't use the the TSC to accumulate time. > > > We are instead interpolating between timer ticks and the TSC, where > > > > Yes, it was supposed to be simple, so that Andrea understands that > > there's nothing inherently broken with single-shot timers. > > Just a quick comment; The timer does not need to be single-shot > all the time, it can be a combination of continuous and variable > length timer, and it can change depending on the system load. > > We recently added VST support for OMAP in linux-omap bk tree, and > made some changes to the previous VST implementations that might be > of interest: ... > The patch in question is at: > > http://linux-omap.bkbits.net:8080/main/user=tmlind/patch@1.2016.4.18?nav=!-|index.html|stats|!+|index.html|ChangeSet@-12w|cset@1.2016.4.18 Wow, that's basically 8 lines of code plus driver for new hardware... Is it really that simple? Pavel -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!