Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755429Ab2BUS0w (ORCPT ); Tue, 21 Feb 2012 13:26:52 -0500 Received: from mail-wi0-f174.google.com ([209.85.212.174]:60674 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754676Ab2BUS0v (ORCPT ); Tue, 21 Feb 2012 13:26:51 -0500 Authentication-Results: mr.google.com; spf=pass (google.com: domain of linus971@gmail.com designates 10.180.14.193 as permitted sender) smtp.mail=linus971@gmail.com; dkim=pass header.i=linus971@gmail.com MIME-Version: 1.0 In-Reply-To: <4F43DB69.9060509@zytor.com> References: <4F42FE08.5020309@zytor.com> <4F43DB69.9060509@zytor.com> From: Linus Torvalds Date: Tue, 21 Feb 2012 10:26:30 -0800 X-Google-Sender-Auth: eUc8S7MbZGphsdTuryGrsjM37SY Message-ID: Subject: Re: [PATCH v2 3/3] i387: support lazy restore of FPU state To: "H. Peter Anvin" Cc: Josh Boyer , Jongman Heo , Thomas Gleixner , Ingo Molnar , x86@kernel.org, Linux Kernel Mailing List Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1672 Lines: 41 On Tue, Feb 21, 2012 at 9:59 AM, H. Peter Anvin wrote: > > I don't know if unlazy_fpu() being out of line will cause a context > switch performance loss, though. unlazy_fpu() is no longer used for context switching - it's only used for unlazying the FPU. Part of the whole FP mess is that there were all these *insane* dependencies where these things were used for different semantic issues. That's largely fixed now, and things have a single semantic use. > Acked-by: H. Peter Anvin > > Let me know if you'd prefer me to pull this into the -tip tree. Yes, but I'll send you this with a proper commit log. I'll also send you another patch that splits "" into two. Right now has two different users: the first of which "normal kernel use" kind of things (ie kernel_fpu_begin() and friends) that really don't care about the internals very deeply. But the second class of user is the actual i387 internal implementation thing that is used by i387.c and xsave.c etc to actually implement the exposed interfaces. As a result, is this mixture of exposed interfaces and "deep internal knowledge". And as a result, that deep internal knowledge kind of accidentally gets exposed to code that really shouldn't be exposed to it. I have a patch that fixes that. I'll send you a series of two patches with sign-offs and commentary asap. Linus -- 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/