From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 03 Mar 2014 15:05:44 +0100 (CET) Received: from mailapp01.imgtec.com ([195.89.28.114]:59463 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6822287AbaCCOFkPjvFB (ORCPT ); Mon, 3 Mar 2014 15:05:40 +0100 Received: from KLMAIL01.kl.imgtec.org (unknown [192.168.5.35]) by Websense Email Security Gateway with ESMTPS id 36F7FFE77B0A4; Mon, 3 Mar 2014 14:05:32 +0000 (GMT) Received: from LEMAIL01.le.imgtec.org (192.168.152.62) by KLMAIL01.kl.imgtec.org (192.168.5.35) with Microsoft SMTP Server (TLS) id 14.3.174.1; Mon, 3 Mar 2014 14:05:34 +0000 Received: from [192.168.154.47] (192.168.154.47) by LEMAIL01.le.imgtec.org (192.168.152.62) with Microsoft SMTP Server (TLS) id 14.3.174.1; Mon, 3 Mar 2014 14:05:33 +0000 Message-ID: <53148C5A.7020101@imgtec.com> Date: Mon, 3 Mar 2014 14:06:18 +0000 From: Markos Chandras User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Ralf Baechle CC: , Paul Burton Subject: Re: [PATCH 3/5] MIPS: Set page size to 16KB for malta SMP defconfigs References: <1392904828-12969-1-git-send-email-markos.chandras@imgtec.com> <1392904828-12969-4-git-send-email-markos.chandras@imgtec.com> <20140221173829.GI19285@linux-mips.org> In-Reply-To: <20140221173829.GI19285@linux-mips.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.154.47] Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 39397 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: Markos.Chandras@imgtec.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On 02/21/2014 05:38 PM, Ralf Baechle wrote: > On Thu, Feb 20, 2014 at 02:00:26PM +0000, Markos Chandras wrote: > >> From: Paul Burton >> >> For Malta defconfigs which may run on an SMP configuration without >> hardware cache anti-aliasing, a 16KB page size is a safer default. >> Most notably at the moment it will avoid cache aliasing issues for >> multicore proAptiv systems. > > You're aware that this may cause binary compatibility issues with old > userland? So far the defaults were chosen to maximise compatibility > over performance. > > Ralf > Hi Ralf, Are you referring to programs hard coding the page size to 4k instead of using the getpagesize()? Well yes this could be a problem. But is that a real problem? We are changing the default value so whoever has such an old userland can easily switch to the 4k page size. It may also be a good opportunity to expose such application and get the fixed properly :) But if that's not acceptable, we can drop the patch. Paul what do you think? -- markos From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailapp01.imgtec.com ([195.89.28.114]:59463 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6822287AbaCCOFkPjvFB (ORCPT ); Mon, 3 Mar 2014 15:05:40 +0100 Message-ID: <53148C5A.7020101@imgtec.com> Date: Mon, 3 Mar 2014 14:06:18 +0000 From: Markos Chandras MIME-Version: 1.0 Subject: Re: [PATCH 3/5] MIPS: Set page size to 16KB for malta SMP defconfigs References: <1392904828-12969-1-git-send-email-markos.chandras@imgtec.com> <1392904828-12969-4-git-send-email-markos.chandras@imgtec.com> <20140221173829.GI19285@linux-mips.org> In-Reply-To: <20140221173829.GI19285@linux-mips.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-Path: Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-subscribe: List-owner: List-post: List-archive: To: Ralf Baechle Cc: linux-mips@linux-mips.org, Paul Burton Message-ID: <20140303140618.WlDpawrRUtmblDLyP5PgPU4-tC-qvOqcEq6A5HPzDQM@z> On 02/21/2014 05:38 PM, Ralf Baechle wrote: > On Thu, Feb 20, 2014 at 02:00:26PM +0000, Markos Chandras wrote: > >> From: Paul Burton >> >> For Malta defconfigs which may run on an SMP configuration without >> hardware cache anti-aliasing, a 16KB page size is a safer default. >> Most notably at the moment it will avoid cache aliasing issues for >> multicore proAptiv systems. > > You're aware that this may cause binary compatibility issues with old > userland? So far the defaults were chosen to maximise compatibility > over performance. > > Ralf > Hi Ralf, Are you referring to programs hard coding the page size to 4k instead of using the getpagesize()? Well yes this could be a problem. But is that a real problem? We are changing the default value so whoever has such an old userland can easily switch to the 4k page size. It may also be a good opportunity to expose such application and get the fixed properly :) But if that's not acceptable, we can drop the patch. Paul what do you think? -- markos