Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932278AbWAFRSw (ORCPT ); Fri, 6 Jan 2006 12:18:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932356AbWAFRSw (ORCPT ); Fri, 6 Jan 2006 12:18:52 -0500 Received: from mail.dvmed.net ([216.237.124.58]:62123 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S932278AbWAFRSv (ORCPT ); Fri, 6 Jan 2006 12:18:51 -0500 Message-ID: <43BEA672.4010309@pobox.com> Date: Fri, 06 Jan 2006 12:18:42 -0500 From: Jeff Garzik User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Arjan van de Ven CC: linux-kernel@vger.kernel.org, akpm@osdl.org, mingo@elte.hu Subject: Re: [patch 2/7] enable unit-at-a-time optimisations for gcc4 References: <1136543825.2940.8.camel@laptopd505.fenrus.org> <1136543914.2940.11.camel@laptopd505.fenrus.org> In-Reply-To: <1136543914.2940.11.camel@laptopd505.fenrus.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: 0.1 (/) X-Spam-Report: Spam detection software, running on the system "srv2.dvmed.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Arjan van de Ven wrote: > Subject: allow gcc4 to optimize unit-at-a-time > > > From: Ingo Molnar > > allow gcc4 compilers to optimize unit-at-a-time. > > This flag enables gcc to "see" the entire C file before making optimisation > decisions such as inline, which results in gcc making better decisions. One > of the immediate effects of this is that static functions that are used only > once now get inlined. > > gcc 3.4 has this flag as well, however gcc 3.x have a problem with inlining > and stacks and as a result, enabling this flag there would cause excessive > and unacceptable stack use. This problem is fixed in the gcc 4.x series. > The x86-64 architecture already enables this feature so it's well tested > already. > > Signed-off-by: Ingo Molnar > Signed-off-by: Arjan van de Ven [...] Content analysis details: (0.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.1 RCVD_IN_SORBS_DUL RBL: SORBS: sent directly from dynamic IP address [69.134.188.146 listed in dnsbl.sorbs.net] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1362 Lines: 38 Arjan van de Ven wrote: > Subject: allow gcc4 to optimize unit-at-a-time > > > From: Ingo Molnar > > allow gcc4 compilers to optimize unit-at-a-time. > > This flag enables gcc to "see" the entire C file before making optimisation > decisions such as inline, which results in gcc making better decisions. One > of the immediate effects of this is that static functions that are used only > once now get inlined. > > gcc 3.4 has this flag as well, however gcc 3.x have a problem with inlining > and stacks and as a result, enabling this flag there would cause excessive > and unacceptable stack use. This problem is fixed in the gcc 4.x series. > The x86-64 architecture already enables this feature so it's well tested > already. > > Signed-off-by: Ingo Molnar > Signed-off-by: Arjan van de Ven ACK, with a note: gcc also supports limited program-at-a-time -- you pass multiple .c files on the same command line, and specify a single output on the command line. It would be nice to update kbuild to do this for single directory modules.... Jeff - 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/