Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752441AbaGLRb7 (ORCPT ); Sat, 12 Jul 2014 13:31:59 -0400 Received: from mail-qg0-f41.google.com ([209.85.192.41]:59371 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751744AbaGLRb5 (ORCPT ); Sat, 12 Jul 2014 13:31:57 -0400 MIME-Version: 1.0 In-Reply-To: <87tx6mzslt.fsf@rasmusvillemoes.dk> References: <1404993911-10544-1-git-send-email-linux@rasmusvillemoes.dk> <20140710220233.GA21053@google.com> <87tx6mzslt.fsf@rasmusvillemoes.dk> From: Bjorn Helgaas Date: Sat, 12 Jul 2014 11:31:36 -0600 Message-ID: Subject: Re: [PATCH] pci: Add include guard to include/linux/pci_ids.h To: Rasmus Villemoes Cc: "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 12, 2014 at 6:09 AM, Rasmus Villemoes wrote: > Bjorn Helgaas writes: > >> On Thu, Jul 10, 2014 at 02:05:11PM +0200, Rasmus Villemoes wrote: >>> Adding an include guard frees the preprocessor from reparsing over >>> 2600 #defines in the cases where pci_ids.h is somehow included more >>> than once. This gives a tiny-but-measurable performance improvement >>> when compiling such files. >>> >>> Signed-off-by: Rasmus Villemoes >> >> Applied to pci/misc for v3.17, thanks! >> > > Great. > > One thing I thought about, but which is likely undoable in practice: > There are only about 800 files which use any of the #defines in > pci_ids.h, but more than 3000 files include pci.h directly or > indirectly. Making those 800 include pci_ids.h directly and removing it > from pci.h could speed up compilation of the other 2200. Yeah, changing 800 files for a minor build performance improvement doesn't sound like it'd be worth the churn. Bjorn -- 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/