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=-4.0 required=3.0 tests=BAYES_00,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 96973C433E0 for ; Fri, 26 Mar 2021 15:34:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 57DBC61A26 for ; Fri, 26 Mar 2021 15:34:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230247AbhCZPeQ (ORCPT ); Fri, 26 Mar 2021 11:34:16 -0400 Received: from mail-ed1-f43.google.com ([209.85.208.43]:44909 "EHLO mail-ed1-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230106AbhCZPd7 (ORCPT ); Fri, 26 Mar 2021 11:33:59 -0400 Received: by mail-ed1-f43.google.com with SMTP id j3so6747368edp.11; Fri, 26 Mar 2021 08:33:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=fVuyITToMefSsVdcKHUKULd5V5yD+yduTs+fYSCVCoA=; b=iBvkvUNql4vCso3sQzClsmMP16IhO+tkBsv+mLHfkbJXDn4hrg6GgSGHFdMxF67hGe kDq9CQrZxRW1peVtsipG8L+x4zy8nKlOwl7EokTCmmrULT8vsqNf+8U4L+Hzm734Cneb uvHCMUtzQ4JdeBOgHMs/ioCBhEWtP0ypmd+uiUaMg2V21nIKvATlYtrEooGOipgE1Y2f UCV/1/dM2TBhNn5GI50eCmeHrURMPo7pokITIcAMfs+GZO5kBnns7JhLj5NWaQdEMcCY jyaZJqi8A1a3sTtTrxqT/5tRmoDXPF3Y+WG6M1q66cmjZyk9Zb6l6TLCcgjGQ0hGXRfp Pl+A== X-Gm-Message-State: AOAM530XdvKuKKGZE3I82TTBMbQ29a6H0OEVTcivT8cpU5Rx1853p9LG Bh9SwprApVkun9BR80JRHBGSUy87MPvKPGMWRj0O+0pw X-Google-Smtp-Source: ABdhPJxSkedp8fuIQnTqBygp92MCs6xp3cWITyw3O2utH0HrpIqiVIMyxLv1UpSZKeKtgdfkbJ7ovzgI1X1OBtDclns= X-Received: by 2002:a05:6402:35c9:: with SMTP id z9mr15796150edc.94.1616772838554; Fri, 26 Mar 2021 08:33:58 -0700 (PDT) MIME-Version: 1.0 References: <20210221185637.19281-1-chang.seok.bae@intel.com> <20210221185637.19281-23-chang.seok.bae@intel.com> <871rc9bl3v.fsf@nanos.tec.linutronix.de> In-Reply-To: From: Len Brown Date: Fri, 26 Mar 2021 11:33:47 -0400 Message-ID: Subject: Re: [PATCH v4 22/22] x86/fpu/xstate: Introduce boot-parameters to control state component support To: Andy Lutomirski Cc: Thomas Gleixner , "Chang S. Bae" , Borislav Petkov , Ingo Molnar , X86 ML , "Brown, Len" , Dave Hansen , "Liu, Jing2" , "Ravi V. Shankar" , Linux Kernel Mailing List , Linux Documentation List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 25, 2021 at 9:42 PM Andy Lutomirski wrote: > Regardless of what you call AMX, AMX requires kernel enabling. I submit, that after the generic XFD support is in place, there is exactly 1 bit that needs to be flipped to enable user applications to benefit from AMX. I submit the patch that knows about AMX and double checks the state size is superfluous. I submit that updating /proc/cpuinfo is superfluous. What AMX-specific kernel enabling did I miss? > Specifically, it appears that leaving AMX in use in the XINUSE sense > degrades system performance and/or power. Please share the specifics about what performance or power issue you anticipate. thanks, -Len