Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756248AbXJJBoK (ORCPT ); Tue, 9 Oct 2007 21:44:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754125AbXJJBn5 (ORCPT ); Tue, 9 Oct 2007 21:43:57 -0400 Received: from barikada.upol.cz ([158.194.242.200]:50643 "EHLO barikada.upol.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754002AbXJJBn4 (ORCPT ); Tue, 9 Oct 2007 21:43:56 -0400 Date: Wed, 10 Oct 2007 03:58:08 +0200 To: Valdis.Kletnieks@vt.edu Cc: Joerg Roedel , Andi Kleen , Christoph Egger , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] i386: mce cleanup part1: functional change Message-ID: <20071010015807.GE22435@flower.upol.cz> References: <11919341961890-git-send-email-joerg.roedel@amd.com> <11919341961530-git-send-email-joerg.roedel@amd.com> <20071009160605.GC13205@amd.com> <20071009163230.GC22435@flower.upol.cz> <1152.1191962806@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1152.1191962806@turing-police.cc.vt.edu> User-Agent: Mutt/1.5.13 (2006-08-11) From: Oleg Verych Organization: Palacky University in Olomouc, experimental physics department X-OS: x86_64-pc-linux-glibc-debian Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1343 Lines: 31 On Tue, Oct 09, 2007 at 04:46:46PM -0400, Valdis.Kletnieks@vt.edu wrote: > On Tue, 09 Oct 2007 18:32:30 +0200, Oleg Verych said: > > On Tue, Oct 09, 2007 at 06:06:05PM +0200, Joerg Roedel wrote: > > > > cpu_has() returns int, > > > > but would it be better to have something like > > > > > > > > if (!mce_disabled && > > > > !(c->x86_capability & (X86_FEATURE_MCA | X86_FEATURE_MCE)) { > > > > printk(KERN_INFO "CPU%i: No machine check support available\n", > > > > smp_processor_id()); > > > > > > This looks complicated and is harder to read. Its exactly the purpose of the > > > cpu_has() macro to avoid such constructs. > > > > It is done via test_bit(), which is designed for IO access with all that > > `const volatile' stuff, 2 x unnecessary, can't be optimized here (IMHO). > > If this code is getting called often enough that optimization matters, you > got *bigger* issues to worry about than optimization. Looks like it should > only happen once at boot time. Text size matters even on static storages. A Linuxbios image not fitting to the 2M flash, etc. Thanks. ____ - 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/