From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933453Ab1ERS0N (ORCPT ); Wed, 18 May 2011 14:26:13 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:58720 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933393Ab1ERS0K (ORCPT ); Wed, 18 May 2011 14:26:10 -0400 Date: Wed, 18 May 2011 20:26:05 +0200 From: Ingo Molnar To: Nikhil Rao Cc: Peter Zijlstra , Mike Galbraith , linux-kernel@vger.kernel.org, "Nikunj A. Dadhania" , Srivatsa Vaddagiri , Stephan Barwolf Subject: Re: [PATCH v2 3/3] sched: increase SCHED_LOAD_SCALE resolution Message-ID: <20110518182605.GC25881@elte.hu> References: <1305738580-9924-1-git-send-email-ncrao@google.com> <1305738580-9924-4-git-send-email-ncrao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1305738580-9924-4-git-send-email-ncrao@google.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Nikhil Rao wrote: > /* > - * Increase resolution of nice-level calculations: > + * Increase resolution of nice-level calculations for 64-bit architectures. > */ > -#define SCHED_LOAD_SHIFT 10 > +#if BITS_PER_LONG > 32 > +#define SCHED_LOAD_RESOLUTION 10 > +#define scale_load(w) (w << SCHED_LOAD_RESOLUTION) > +#define scale_load_down(w) (w >> SCHED_LOAD_RESOLUTION) > +#else > +#define SCHED_LOAD_RESOLUTION 0 > +#define scale_load(w) w > +#define scale_load_down(w) w > +#endif Please also be a bit more verbose in the comment above why we treat 64-bit architectures differently - it's not obvious. Thanks, Ingo