From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8EA9C433E0 for ; Mon, 18 May 2020 12:34:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9ADD020787 for ; Mon, 18 May 2020 12:34:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589805242; bh=HaY3ABwfaRO6UoNgRn0bHMV0yl53SNp5iJWDXXT9BPk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=AhAdB0fhI7yoB5YifclgaGdSRP+77bT4SxqDkh/YNBZepDavjdUBKtBURfJubz+OS hwMuhmasWg/b1F+LFILVKe47SDL+dPVCdPbiQIxKDfbkOSWecVU2+ZmiyCVAHeOJBJ M/OqOorPF/p3APoOyEToujVVpmYvCtmjShJG6q6I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727020AbgERMeB (ORCPT ); Mon, 18 May 2020 08:34:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:35286 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726800AbgERMeB (ORCPT ); Mon, 18 May 2020 08:34:01 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DB34120657; Mon, 18 May 2020 12:34:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589805241; bh=HaY3ABwfaRO6UoNgRn0bHMV0yl53SNp5iJWDXXT9BPk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iTIot6i8i/rMUu0LpUwSA3/CrD7rN47ZuKU6rxdlLVSiHIcM4AwgItpxYOm5FRAdE UvUVqk/hAy+Bs68TL8l4zuCqxQ+T14akon6FrWCNabDo+pcMTKl4FknUqHoyiaMlw6 bQaPVtCUPUJwMwSjsWTui942qqdacj4+qW1OzIfk= Date: Mon, 18 May 2020 08:33:59 -0400 From: Sasha Levin To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, luto@kernel.org, hpa@zytor.com, dave.hansen@intel.com, tony.luck@intel.com, ak@linux.intel.com, ravi.v.shankar@intel.com, chang.seok.bae@intel.com Subject: Re: [PATCH v12 00/18] Enable FSGSBASE instructions Message-ID: <20200518123359.GB33628@sasha-vm> References: <20200511045311.4785-1-sashal@kernel.org> <20200518061836.GA15641@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200518061836.GA15641@infradead.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 17, 2020 at 11:18:36PM -0700, Christoph Hellwig wrote: >On Mon, May 11, 2020 at 12:52:53AM -0400, Sasha Levin wrote: >> Benefits: >> Currently a user process that wishes to read or write the FS/GS base must >> make a system call. But recent X86 processors have added new instructions >> for use in 64-bit mode that allow direct access to the FS and GS segment >> base addresses. The operating system controls whether applications can >> use these instructions with a %cr4 control bit. >> >> In addition to benefits to applications, performance improvements to the >> OS context switch code are possible by making use of these instructions. A >> third party reported out promising performance numbers out of their >> initial benchmarking of the previous version of this patch series [9]. > >The [9] reference can't be resolved anywhere in this mail. Sorry, I'll fix it up. The reference was supposed to be pointing to: https://www.phoronix.com/scan.php?page=article&item=linux-wip-fsgsbase&num=1 -- Thanks, Sasha