From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753080AbbBWPwn (ORCPT ); Mon, 23 Feb 2015 10:52:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51339 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751948AbbBWPwm (ORCPT ); Mon, 23 Feb 2015 10:52:42 -0500 Message-ID: <54EB4C7E.7010706@redhat.com> Date: Mon, 23 Feb 2015 10:51:26 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Borislav Petkov CC: Andy Lutomirski , "Maciej W. Rozycki" , Ingo Molnar , Oleg Nesterov , X86 ML , "linux-kernel@vger.kernel.org" , Linus Torvalds Subject: Re: [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs References: <20150221093150.GA27841@gmail.com> <20150221163840.GA32073@pd.tnic> <20150221172914.GB32073@pd.tnic> <20150222110629.GB7529@pd.tnic> <54EA8641.6040609@redhat.com> <54EB2238.7010005@redhat.com> <20150223150350.GB22753@pd.tnic> In-Reply-To: <20150223150350.GB22753@pd.tnic> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 02/23/2015 10:03 AM, Borislav Petkov wrote: > On Mon, Feb 23, 2015 at 07:51:04AM -0500, Rik van Riel wrote: >> At that point we either load the FPU context, or we set CR0.TS. > > Right, but provided eager doesn't bring any slowdown, we can drop > the TS fiddling altogether and only load FPU context. Agreed. However, we would still need the rest of the kernel code to check whether userspace FPU context is loaded in the registers or not. We cannot simplify to the point of assuming that the FPU state will always be loaded when in eager mode. - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJU60x+AAoJEM553pKExN6DIMkIAJpZHQuojQMTUyy11EB7dx2N ZMm5PiQGW47f/BIbIwR3hwZbC385ZLdx1Nkrys8cXd3WNJInrMxf2PDaU9YtDFw1 NdybRbbsxAAaB3oJldLFUH5ouo9ePKV4RyXFgsgNH75uv6u4pesaWwUZNuLmxzrk h8/wns7Lpddr4C0ahPimEM1pXdfiFyo/0jaAiOj8o/IklXiJW25LBYUzE4ogD/2T 097wV5C8ojvS4doVD+GthxFuJFslZWxyNaRBRNqpE2LyhmjEdz2WwNTSrDtLsBK0 gKHjgD0eox/HpNkBzwaF6MOo1of2/WFNSJyRKwlwaWnRNpZ3jDfyU0VPg3yhF30= =aIKn -----END PGP SIGNATURE-----