Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 21 Jan 2002 12:09:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 21 Jan 2002 12:09:44 -0500 Received: from mail.loewe-komp.de ([62.156.155.230]:59147 "EHLO mail.loewe-komp.de") by vger.kernel.org with ESMTP id ; Mon, 21 Jan 2002 12:09:41 -0500 Message-ID: <3C4C4C1A.9F7CE37@loewe-komp.de> Date: Mon, 21 Jan 2002 18:12:58 +0100 From: Peter =?iso-8859-1?Q?W=E4chtler?= Organization: LOEWE. Hannover X-Mailer: Mozilla 4.78 [de] (X11; U; Linux 2.4.16 i686) X-Accept-Language: de, en MIME-Version: 1.0 To: yodaiken@fsmlabs.com CC: Daniel Phillips , george anzinger , Momchil Velikov , Arjan van de Ven , Roman Zippel , linux-kernel@vger.kernel.org Subject: Re: [2.4.17/18pre] VM and swap - it's really unusable In-Reply-To:

<20020121084344.A13455@hq.fsmlabs.com> <20020121090602.A13715@hq.fsmlabs.com> <3C4C42EE.BAEBE8CB@loewe-komp.de> <20020121094554.A14139@hq.fsmlabs.com> Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org yodaiken@fsmlabs.com schrieb: > > On Mon, Jan 21, 2002 at 05:33:50PM +0100, Peter W?chtler wrote: > > yodaiken@fsmlabs.com schrieb: > > > > > > On Mon, Jan 21, 2002 at 05:05:01PM +0100, Daniel Phillips wrote: > > > > > I think of "benefit", perhaps naiively, in terms of something that can > > > > > be measured or demonstrated rather than just announced. > > > > > > > > But you see why asap scheduling improves latency/throughput *in theory*, > > > > > > Nope. And I don't even see a relationship between preemption and asap I/O > > > schedulding. What make you think that I/O threads won't be preempted by > > > other threads? > > > > > > > I/O intensive threads block early voluntarily - while CPU hogs don't. > > Since the preemption patch only allows additional preemption in kernel > mode, I'm curious to know what the compute bound tasks are doing in > kernel mode. Did Linux add in-kernel matrix multiplication while > I was not looking? > Dead right you are. Then there are only slow system calls left. Umh, execve(), fork() (with big address space) - what about page_launder etc.? > > Statistically there is a higher chance, that a CPU hog gets preempted > > instead of an IO bound (that gives up the CPU in some useconds anyway) > > "Statistically"? As far as I know, most I/O in Linux does not block. You mean, the syscall returns without a reschedule? Aehm, now it's time for some statistics where the kernel spents its time on ;-) But what is a possible explanation for the people, who think their systems behave better with preemption - strong believe? - 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/