Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759337AbaD3SOo (ORCPT ); Wed, 30 Apr 2014 14:14:44 -0400 Received: from mail-bn1blp0185.outbound.protection.outlook.com ([207.46.163.185]:20364 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752186AbaD3SOn (ORCPT ); Wed, 30 Apr 2014 14:14:43 -0400 Message-ID: <1398881677.24575.197.camel@snotra.buserror.net> Subject: Re: [PATCH] powerpc 32: Provides VIRT_CPU_ACCOUNTING From: Scott Wood To: Benjamin Herrenschmidt CC: Christophe Leroy , Paul Mackerras , , Date: Wed, 30 Apr 2014 13:14:37 -0500 In-Reply-To: <1398833787.31586.8.camel@pasglop> References: <20140319215241.236B21A4BDE@localhost.localdomain> <1395266717.12479.293.camel@snotra.buserror.net> <1398833787.31586.8.camel@pasglop> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [2601:2:5800:3f7:55b5:c8fb:7ca4:3149] X-ClientProxiedBy: BN1PR02CA0043.namprd02.prod.outlook.com (10.141.56.43) To BL2PR03MB388.namprd03.prod.outlook.com (10.141.91.153) X-Forefront-PRVS: 0197AFBD92 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10009001)(6009001)(428001)(24454002)(51704005)(199002)(189002)(377424004)(79102001)(83072002)(93916002)(33646001)(86362001)(101416001)(50986999)(50466002)(85852003)(87976001)(20776003)(47776003)(50226001)(81542001)(4396001)(81342001)(99396002)(80022001)(80976001)(74662001)(74502001)(31966008)(62966002)(89996001)(92726001)(77982001)(42186004)(87286001)(23676002)(76176999)(77156001)(92566001)(83322001)(76482001)(46102001)(88136002)(3826001);DIR:OUT;SFP:1101;SCL:1;SRVR:BL2PR03MB388;H:[IPv6:2601:2:5800:3f7:55b5:c8fb:7ca4:3149];FPR:;MLV:sfv;PTR:InfoNoRecords;A:1;MX:1;LANG:en; Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=scottwood@freescale.com; X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-04-30 at 14:56 +1000, Benjamin Herrenschmidt wrote: > On Wed, 2014-03-19 at 17:05 -0500, Scott Wood wrote: > > On Wed, 2014-03-19 at 22:52 +0100, Christophe Leroy wrote: > > > This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture. > > > Unlike PPC64, PPC32 doesn't provide the PACA register. Therefore the > > > implementation is similar to the one done in the IA64 architecture. > > > It is based on additional information added to the Task Info structure. > > > > PACA isn't a register -- just a convention for how Linux uses a GPR. > > Maybe it's time to use it on PPC32 as well? > > PACA is actually a data structure and you really really don't want it > on ppc32 :-) Having a register point to current works, having a register > point to per-cpu data instead works too (ie, change what we do today), > but don't introduce a PACA *please* :-) What is special about 64-bit that warrants doing things differently from 32-bit? What is the difference between PACA and "per-cpu data", other than the obscure name? -Scott -- 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/