Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263984AbUDVMP3 (ORCPT ); Thu, 22 Apr 2004 08:15:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263989AbUDVMP3 (ORCPT ); Thu, 22 Apr 2004 08:15:29 -0400 Received: from mtagate1.de.ibm.com ([195.212.29.150]:11684 "EHLO mtagate1.de.ibm.com") by vger.kernel.org with ESMTP id S263986AbUDVMP1 (ORCPT ); Thu, 22 Apr 2004 08:15:27 -0400 Subject: Re: [PATCH] s390 (9/9): no timer interrupts in idle. To: Arjan van de Ven Cc: akpm@osdl.org, linux-kernel@vger.kernel.org X-Mailer: Lotus Notes Release 5.0.11 July 24, 2002 Message-ID: From: Martin Schwidefsky Date: Thu, 22 Apr 2004 14:14:44 +0200 X-MIMETrack: Serialize by Router on D12ML062/12/M/IBM(Release 6.0.2CF2|July 23, 2003) at 22/04/2004 14:14:46 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 Content-Length: 1265 Lines: 33 > ok maybe I need to word it differently. > What I'm proposing as alternative is using the one shot mode of the timers > on most machines to do teh following: > when the timer irq hits, you do the business you need to do. And then you > check all existing timers and the scheduler when the next "virtual tick" is where > you're going to do real work. You then set the one-shot counter to that > amount. This means that in add_timer/mod_timer you will need to check if the > just added timer is before the current one-shot runs out, and if so, adjust > it. Perhaps in the scheduler too. You can't do that with the current timer code. A HZ timer interrupt is used for several things: 1) increase jiffies_64, 2) update the xtime, 3) calculate the load every 5 seconds, 4) check cpu time limits and send SIGXCPU, 5) do interval timer stuff, 6) run local timer queue and 7) add time slice to current process. With your one-shot timer you won't do the correct updates to the jiffies and the xtime. blue skies, Martin - 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/