Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261716AbUKABof (ORCPT ); Sun, 31 Oct 2004 20:44:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261500AbUKABod (ORCPT ); Sun, 31 Oct 2004 20:44:33 -0500 Received: from holomorphy.com ([207.189.100.168]:23170 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S261716AbUKABms (ORCPT ); Sun, 31 Oct 2004 20:42:48 -0500 Date: Sun, 31 Oct 2004 17:42:30 -0800 From: William Lee Irwin III To: Pavel Machek Cc: Con Kolivas , linux kernel mailing list , Andrew Morton , Ingo Molnar , Peter Williams , Alexander Nyberg , Nick Piggin Subject: Re: [PATCH][plugsched 0/28] Pluggable cpu scheduler framework Message-ID: <20041101014230.GC2583@holomorphy.com> References: <4183A602.7090403@kolivas.org> <20041031233313.GB6909@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041031233313.GB6909@elf.ucw.cz> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.6+20040722i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1196 Lines: 28 At some point in the past, Con Kolivas wrote: >> This code was designed to touch the least number of files, be completely >> arch-independant, and allow extra schedulers to be coded in by only >> touching Kconfig, scheduler.c and scheduler.h. It should incur no >> overhead when run and will allow you to compile in only the scheduler(s) >> you desire. This allows, for example, embedded hardware to have a tiny >> new scheduler that takes up minimal code space. On Mon, Nov 01, 2004 at 12:33:13AM +0100, Pavel Machek wrote: > You are changing > some_functions() > into > something->function() > no? I do not think that is 0 overhead... It's nonzero, yes. However, it's rather small with modern branch predictors; older microarchitectures handled this less well, which is probably why you expect a measurable hit. It may still have non-negligible performance effects on some legacy architectures, but I would not let that hold up progress. -- wli - 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/