From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752083AbaEZTh3 (ORCPT ); Mon, 26 May 2014 15:37:29 -0400 Received: from mail-pb0-f51.google.com ([209.85.160.51]:45694 "EHLO mail-pb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751796AbaEZTh2 (ORCPT ); Mon, 26 May 2014 15:37:28 -0400 Message-ID: <538397F5.6010002@amacapital.net> Date: Mon, 26 May 2014 12:37:25 -0700 From: Andy Lutomirski User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Fenghua Yu , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Asit K Mallick CC: linux-kernel , x86 Subject: Re: [PATCH 0/15] x86/xsaves: Optimize xstate context switch by xsaves/xrstors References: <1401123682-5384-1-git-send-email-fenghua.yu@intel.com> In-Reply-To: <1401123682-5384-1-git-send-email-fenghua.yu@intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/26/2014 10:01 AM, Fenghua Yu wrote: > From: Fenghua Yu > > With ever growing extended state registers (xstate) on x86 processors, kernel > needs to cope with issue of growing memory space occupied by xstate. The xsave > area is holding more and more xstate registers, growing from legacy FP and > SSE to AVX, AVX2, AVX-512, MPX, and Intel PT. > > The recently introduced compacted format of xsave area saves xstates only > for enabled states. This patch set saves the xsave area space per process > in compacted format by xsaves/xrstors instructions. Are we going to want to encourage userspace to do something like sticking vzeroupper right before each syscall to make any xsaves/xrestores faster? --Andy