From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 4 Jun 2001 19:09:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 4 Jun 2001 19:08:51 -0400 Received: from gateway.sequent.com ([192.148.1.10]:721 "EHLO gateway.sequent.com") by vger.kernel.org with ESMTP id ; Mon, 4 Jun 2001 19:08:47 -0400 Date: Mon, 4 Jun 2001 16:08:37 -0700 From: Mike Kravetz To: linux-kernel@vger.kernel.org Subject: reschedule_idle changes in ac kernels Message-ID: <20010604160837.B15640@w-mikek2.des.sequent.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I just noticed the changes to reschedule_idle() in the 2.4.5-ac kernel. I suspect these are the changes made for: o Fix off by one on real time pre-emption in scheduler I'm curious if anyone has ran any benchmarks before and after applying this fix. The reason I ask is that during the development of my multi-queue scheduler, I 'accidently' changed reschedule_idle code to trigger a preemption if preemption_goodness() was greater than 0, as opposed to greater than 1. I believe this is the same change made to the ac kernel. After this change, we saw a noticeable drop in performance for some benchmarks. The drop in performance I saw could have been the result of a combination of the change, and my multi-queue scheduler. However, in any case aren't we now going to trigger more preemptions? I understand that we need to make the fig to get the realtime semantics correct, but we also need to be aware of performance in the non-realtime case. -- Mike Kravetz mkravetz@sequent.com IBM Linux Technology Center