Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934427AbcCNOgO (ORCPT ); Mon, 14 Mar 2016 10:36:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42904 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932705AbcCNOgM (ORCPT ); Mon, 14 Mar 2016 10:36:12 -0400 From: Jeff Moyer To: Denys Vlasenko Cc: Al Viro , Jens Axboe , Christoph Hellwig , linux-kernel@vger.kernel.org Subject: Re: [PATCH] direct-io: Deinline submit_page_section, save 5304 bytes References: <1457902836-30786-1-git-send-email-dvlasenk@redhat.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Mon, 14 Mar 2016 10:36:10 -0400 In-Reply-To: <1457902836-30786-1-git-send-email-dvlasenk@redhat.com> (Denys Vlasenko's message of "Sun, 13 Mar 2016 22:00:34 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 838 Lines: 30 Denys Vlasenko writes: > This function compiles to 2628 bytes, 2 callsites > > text data bss dec hex filename > 15197 16 0 15213 3b6d direct-io.o.before1 > 9655 16 0 9671 25c7 direct-io.o And what is the consequence for performance? If you look at the git history for this file, you'll find the commit that introduced the inline: commit ba253fbf6d3502c54e1ac8792e7ac8290a1f5b8d Author: Andi Kleen Date: Mon Aug 1 21:38:08 2011 -0700 direct-io: inline the complete submission path Add inlines to all the submission path functions. While this increases code size it also gives gcc a lot of optimization opportunities in this critical hotpath. ... So you're essentially undoing that work. NAK Cheers, Jeff