Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261873AbVEKEXy (ORCPT ); Wed, 11 May 2005 00:23:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261874AbVEKEXx (ORCPT ); Wed, 11 May 2005 00:23:53 -0400 Received: from wproxy.gmail.com ([64.233.184.206]:16586 "EHLO wproxy.gmail.com") by vger.kernel.org with ESMTP id S261873AbVEKEXv convert rfc822-to-8bit (ORCPT ); Wed, 11 May 2005 00:23:51 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=o3oNLFfsBEJHAeJjyC4D4DOxArCicw0GwuXT28qNzGwBmv5+iessHPZ1TOswSYW3TsAnHCdABsNf21OhieyFZcK3PqdKRfotvDUk8mI1GBd5wMOJ3zQ3+pMA83tK15tSgDlrVdXI5LtvSOoMzaoRTLeXKQkhJPHu/IzFd2G9WnE= Message-ID: Date: Wed, 11 May 2005 00:23:51 -0400 From: Haoqiang Zheng Reply-To: Haoqiang Zheng To: Con Kolivas Subject: Re: [RFC PATCH] swap-sched: schedule with dynamic dependency detection (2.6.12-rc3) Cc: linux-kernel@vger.kernel.org In-Reply-To: <200505091557.32810.kernel@kolivas.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <200505090926.59335.kernel@kolivas.org> <200505091557.32810.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1780 Lines: 33 > While your swap-sched allows tasks waiting on other tasks to run better, it > also introduces a greater degree of unfairness in cpu resource sharing. By > allowing the dependent tasks to stay on the runqueue you increase > substantially their share of the resources they would otherwise have gotten. > The whole point of decrementing priority and runqueue expiration is to > maintain fairness and you're introducing another way to delay that system > from working. process_load is not the ideal task to test this unfairness on > this design but even that shows twice as much cpu usage with your own tests. > How do you propose to ensure we maintain fairness in this model ? Sorry for the late response. I was busy with some other projects. AFAIK, there are basically two task properties that can affect its long term CPU allocation: the nice value and the interactiveness. The nice value affects the time slice value. The interactiveness affects the time_slice recharge frequency (an interactive task doesn't expire unless there's an ``expire_starving''). Well, swap-sched doesn't affect a task's time_slice value, but it does has impact on interactivity detection. Currently, Linux detects task interactivity based on ``sleep_average''. With swap-sched, a task with dependency will sleep less than it does in vanilla kernel. I am not sure if ``different'' necessary means bad. But I am sure swap-sched can be modified so that the dependency detection part will work exactly the same way as vanilla kernel. Best regards, Haoqiang - 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/