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, 18 Nov 2002 03:14:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 18 Nov 2002 03:14:34 -0500 Received: from holomorphy.com ([66.224.33.161]:63453 "EHLO holomorphy") by vger.kernel.org with ESMTP id ; Mon, 18 Nov 2002 03:14:33 -0500 Date: Mon, 18 Nov 2002 00:18:54 -0800 From: William Lee Irwin III To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, rml@tech9.net, riel@surriel.com, akpm@zip.com.au Subject: unusual scheduling performance Message-ID: <20021118081854.GJ23425@holomorphy.com> Mail-Followup-To: William Lee Irwin III , linux-kernel@vger.kernel.org, mingo@elte.hu, rml@tech9.net, riel@surriel.com, akpm@zip.com.au Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.25i Organization: The Domain of Holomorphy Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 16x, 2.5.47 kernel compiles take about 26s when the machine is otherwise idle. On 32x, 2.5.47 kernel compiles take about 48s when the machine is otherwise idle. When a single-threaded task consumes an entire cpu, kernel compiles take 36s on 32s when the machine is idle aside from the task consuming that cpu and the kernel compile itself. I suspect the scheduler, because cpu reporting in top(1) shows that a two or more cpu-intensive tasks are concentrated on the same cpu, and some long-lived tasks appear to be "bouncing" across cpus. If someone with knowledge and/or expertise with respect to scheduling semantics could look into this, I would be much obliged. Resolving this would likely address many SMP and/or NUMA scheduling performance issues. Thanks, Bill