From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753292AbbJFQqt (ORCPT ); Tue, 6 Oct 2015 12:46:49 -0400 Received: from mail-by2on0115.outbound.protection.outlook.com ([207.46.100.115]:11740 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752337AbbJFQqp (ORCPT ); Tue, 6 Oct 2015 12:46:45 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=scottwood@freescale.com; Message-ID: <1444149995.5336.282.camel@freescale.com> Subject: Re: [PATCH v2 01/25] powerpc/8xx: Save r3 all the time in DTLB miss handler From: Scott Wood To: Christophe Leroy CC: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , , Date: Tue, 6 Oct 2015 11:46:35 -0500 In-Reply-To: <5613CE1C.40806@c-s.fr> References: <2d35de4435e873f23d37e3b5b5fb34c64421f136.1442939410.git.christophe.leroy@c-s.fr> <20150928220717.GA6161@home.buserror.net> <5613CE1C.40806@c-s.fr> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.0-fta1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Originating-IP: [50.157.106.250] X-ClientProxiedBy: BY2PR02CA0113.namprd02.prod.outlook.com (25.163.44.167) To CY1PR03MB1488.namprd03.prod.outlook.com (25.163.17.18) X-Microsoft-Exchange-Diagnostics: 1;CY1PR03MB1488;2:A2F/4pz3dA1RKonmP70RoIz4sdcIuUG56LOLVKqvCZNmQMT4JWs/GpIDwZZPzyRJdIGSiVwRO3eMj718NAwcX17oqS4CwTJJwOjCkS1PCZv77pmOJL75VodlAM32haQAJN0cQKk8rgqjUvJa13hs6mwUUEiAMS4uQipOHyS+mbQ=;3:kEgsY/eY7QbWW+7XSES8bGdge5tc6UFDjKgXV3SIGnQW7iphTZr37L6NuvTJyCvBStyWu9BD1QUwlh78Qfa4Rh+Z8ZlcIODiyIp8OuiJVgOsNiCS3Y4wnRxuGnZQ98SWk0ytzgN4SxZHZGntCkCh1g==;25:YJAll4wuXptm2IwK2KbBTSIIjFyFGRpRkn805Nd+U0hntC9M1CEq9zCOazx+DGL2dz5+mJLbLnl1y3etmDg7qpTsON//vfytcnGnD/BsjyHfkH4KxwiNhlxFMcw+gE2y7EQTjshZesQPgRhajo6gPsDU++8hEyr5ETIenY0lKsFH6FpmJgiOKHmG0nb3vam+/b2WVKDWYHfgDMDGk0UCfCFD+HyqvN7KHAVb17hs19Dj1oApgW+jW7TKaFavwwBB X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:CY1PR03MB1488; X-Microsoft-Exchange-Diagnostics: 1;CY1PR03MB1488;20:SI5jyejD9RCXzNXmINbF153KzPC52SG4XU7Iaarc3iYWvnefSMDb4ec+/Rsdf1eVhDmdeD98IEjZoKGde4LGl4ndz/BRgcmF/zKEk4nytx6U/fwzBKiikYmkwAe9II9GoN/APfN+2lJL5QnWFWpi7A1Uf1ZabfU9T/j0iZDP82ytCWShapZns3YlL3WO+KEZW6wBjd0ti374o9poyd+Taz65sf46D5AN4oFXuol+vydWLzK7zbCwJw8ZbW9Tt6FzHbe670WMpH7HkxVzQCM+bkO+gn8Lp+3oOlGlCmMXBVbeamX9fcmo8STzzYsJhMpal2MrwbLIqxtUMkgo7oDKddHkj1wYX8NybgrUgNQDugUVOaGkKneXkS93VUAGXJiy90gXz1B3IKvPzdo6V9ryQTeXKkww/SCFVJbsWPXUtR73CTGCYzN58GMG6csaLe3RtD41yEqk5dEbbNx3FFWq0dusvZnIjeoW6n0M0SPCKJ/hLVr047zrxI3EUtKU3Tqu;4:TyEOmtTbO+f9hONtv3TFDTxaqg7542bxnI637U9qGRB/Y2fDC4gqAMhJ5FtT3SAckIbQwjF4HEW005AZFuIEvJKPPxZSjdL/tjYfY4iIyu3/vumgdP+HbgwU8fmJc+uX798cY4hEApb3Ut8XSCKYMgKoScGNypeJ8iKFg48iKE76HXaovvHf975nB33WHZHCfq+QOUHF3H13LdgnIQ/27IF0gfU3qjW6h2CKQtSYoNeu45sYgNBJyVV2AhlAq9oyMe+J+4iK7YJHypF/BjWZZV3k5TPh3A8KAZ/sd0XoB8o0pLy4TErgm6ttpmu+y9tKCKOqwOH4AbCYwN5A5JtXYg6+KRqjIm8mVlh0n68G3ts= X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(601004)(2401047)(8121501046)(520078)(5005006)(3002001);SRVR:CY1PR03MB1488;BCL:0;PCL:0;RULEID:;SRVR:CY1PR03MB1488; X-Forefront-PRVS: 07215D0470 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(6009001)(24454002)(199003)(479174004)(377424004)(189002)(189998001)(64706001)(5820100001)(92566002)(2950100001)(36756003)(50226001)(5001960100002)(66066001)(81156007)(5004730100002)(42186005)(5007970100001)(46102003)(110136002)(5008740100001)(93886004)(106356001)(47776003)(77096005)(87976001)(97736004)(50986999)(33646002)(23676002)(19580405001)(105586002)(76176999)(40100003)(101416001)(103116003)(122386002)(86362001)(50466002)(99106002);DIR:OUT;SFP:1102;SCL:1;SRVR:CY1PR03MB1488;H:snotra.local;FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; X-Microsoft-Exchange-Diagnostics: =?utf-8?B?MTtDWTFQUjAzTUIxNDg4OzIzOnlqMkRSUDVtbkt6bzV2dXdFRjAvK2tMS0Nt?= =?utf-8?B?cmZPWWQ5V2pXSUdWTlFDZnJFQnZMMmJ2TVd6TjYwN1hNTnBuenNHWjhUakpI?= =?utf-8?B?R2t1eEI2cEFHNmN5QzJ5ZmtYQkZoUGM0YUZxdzhYcWFxMFFmNFl3UHkrZHI2?= =?utf-8?B?Wk9qMzhjTlNDRnRGbHdVcUFFU0cxaUhhWUUvcUlOYzJxaW9lSjY3bzFVM1pj?= =?utf-8?B?MytDTGx1U3MwS3NDaDllcG5PaWhvM3NIYWliVVJEeEtQd3NTemJxb0dQNDY0?= =?utf-8?B?Tm9Za3FBd0VtRVgvQjJrRitzbTFJM01UaWsvUjlxNkw2TExFVjZpN3Rtcmcr?= =?utf-8?B?eUh0dFVhRXRJV0JENHBJM24xdmZ1bTRROFRub2VJN1ZYY2VqbFUrODcxNU5v?= =?utf-8?B?WmRSQUtMMk9hOFdYU1l1NUw3UDY5bEJSei9CZFowYmYzcUFrcU9ydUE2U0tK?= =?utf-8?B?WVlOUFNJUDloL1IxdElsY2IrWXFSR3EraW9FZkpSWGxRU1o5R001aUNWeG52?= =?utf-8?B?ci8rUUxaL0xsUE5HQ0pTMVM0UnVkTzlEUis3Yzd5ZTRFejMreEhHL2M0NGM3?= =?utf-8?B?M290MzFiKzlRejZSU2dGVjhZRHIyazFxd204U01ET21oZ25xMEVDbzNQcHhh?= =?utf-8?B?SlU5VElQU3A0WW5udG80Q1ZIQ2ZGOFdlWHhKbVg3TkxKS2FTYTNPNUpyN3Mr?= =?utf-8?B?RmdObnBjQUxnZWwzT2NNTG9sK1VrMVM3aUlhdGt3bzAyYXlXNjBEcWVYNGlp?= =?utf-8?B?azlNVUZQTVYzY3M0anJST0JHWSttUUkwVi80bS9rTmtBcU5vN2ZBQ1prcnNJ?= =?utf-8?B?WXd5TFdpTjJPbW90K1dSRitTUVp4Mkt0dUdzV2t5Q0UzbG4yYnVhajFzWks2?= =?utf-8?B?WXBSTmYvL1NlcERMMUJDazVoQ1hzYUxnNlVBZVF2ZDFaR3lMM05ZUnhQaEtQ?= =?utf-8?B?TVZ6MFB0eDZtcmRXTGxEdlR3NENualZOOUZhMzJjOXo2akMvWXo3Y0lJcWY1?= =?utf-8?B?dW92ZThNOEJ4Nmk1QUlGVjUrb0JBbDNNYVd1bXkyeEIrNFRwMVNLYVZsZ05l?= =?utf-8?B?VFduT1ZnMWRDcmg3aDdVdHhTUkNxbWNrZGNkdWl6bksyUHdMOFJJVjFJQ0xz?= =?utf-8?B?M3JDZDhBNEFGVFZkYndUdXVGM09odGIzWk13QU9CUVNDelkvN0xyekgyR0Mz?= =?utf-8?B?ZFNkUStXVlFBQnZ3ZXI0LzlyU3dHemJYWVN4T1hOdFlZRTNlU1NwQkVLekpz?= =?utf-8?B?NHVJWXd0TVZETkFFOFNycFFvbzFncnBwakRMcE9Jb2dOYTZKSHVMT0o1eE5F?= =?utf-8?B?MEJuak5oVklJM05JY3hhek5WMTlERmwveXFPTTZkQWZqTUJVYjZNVW9FVkRE?= =?utf-8?B?QmFkcGZiWVZ1WTFQY1RMbGNnVFpuQmdPYURSU0w2cWE5MzFlOUtjTisxc0k4?= =?utf-8?B?S3BsTjRvUjVMN3BEVmxKbFAwdlBTUFBFdVZqTExZWGJXck95RnE1OUJqVVB3?= =?utf-8?B?Y3kzUT09?= X-Microsoft-Exchange-Diagnostics: 1;CY1PR03MB1488;5:lZ62r9hxMoNKLBx2YQVLkH6i2q5mLbaQRDaxgtFXcNz1hrGw8AGc+lKP3FgQ7NXjmAqmJ91gQHL6mZj4ego4vgNSEei7IgNxBnIwdzezB3wlRCLb1xVrv6nE+mnYm/eMl3/Jt5IdcapncVtkSkQcuA==;24:BwuWOuQalGfrVBvg1iGTJhgq/Yx5VtH+5FfMK+dISS9y2xjLXpxwLt+2sW4bPYiALOW23U9RBi2zwiPZL1v0SFagOg7Aac1bMmQluP291Xs=;20:/z+bTEUjxgVsaerMv76Ra49uc/H0j8iNoJLQxYbZ99+YCiXMVaupB2i0sORVLa2TcGf5SD6JrHVp5pDby3te1A== SpamDiagnosticOutput: 1:23 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: freescale.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Oct 2015 16:46:42.3911 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1PR03MB1488 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2015-10-06 at 15:35 +0200, Christophe Leroy wrote: > Le 29/09/2015 00:07, Scott Wood a écrit : > > On Tue, Sep 22, 2015 at 06:50:29PM +0200, Christophe Leroy wrote: > > > We are spending between 40 and 160 cycles with a mean of 65 cycles in > > > the TLB handling routines (measured with mftbl) so make it more > > > simple althought it adds one instruction. > > > > > > Signed-off-by: Christophe Leroy > > Does this just make it simpler or does it make it faster? What is the > > performance impact? Is the performance impact seen with or without > > CONFIG_8xx_CPU6 enabled? Without it, it looks like you're adding an > > mtspr/mfspr combo in order to replace one mfspr. > > > > > The performance impact is not noticeable. Theoritically it adds 1 cycle > on a mean of 65 cycles, that is 1.5%. Even in the worst case where we > spend around 10% of the time in TLB handling exceptions, that represents > only 0.15% of the total CPU time. So that's almost nothing. > Behind the fact to get in simpler, the main reason is because I need a > third register for the following patch in the set, otherwise I would > spend a more time saving and restoring CR several times. FWIW, the added instruction is an SPR access and I doubt that's only one cycle. -Scott