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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBBC0C433F5 for ; Mon, 14 Mar 2022 19:19:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244004AbiCNTUn (ORCPT ); Mon, 14 Mar 2022 15:20:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232224AbiCNTUk (ORCPT ); Mon, 14 Mar 2022 15:20:40 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1BB6E01C for ; Mon, 14 Mar 2022 12:19:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647285568; x=1678821568; h=message-id:date:mime-version:to:references:from:subject: in-reply-to:content-transfer-encoding; bh=p+7wxMHOLu381tgfLsoOkZa/Lm4AHERLCRbtcI3ncR8=; b=kDESL6x17gO96uB91JKyvRGiihuwNn6B1DYCl0IFRGLudjnFS1eJGEF8 wsN9YG/7g+I3er31aaXXfuMoX1KClwsTaSg2ZpqfFs+2lFMFnUUA9CFxj N5IVJQkQVYgZqclRnzguiTkuGJEB4bCanFkertmHakD9YJVsqmLifzjAe 2q8qYyUHQ+i67GZRMF0FW91/U3vm9BtNCrni4AFAaribsWRf8TTqcoFXY Zy8MIlrEryEQkvu76Mml95psxbOMYn0gQdLJ5bTIpjWhsWNF+wXDcMCfQ CP0Tj/tWBoLXMB3DrriM2VZN5co9MtxACq2eTDI2FHJwdkNbucAFSkHKc g==; X-IronPort-AV: E=McAfee;i="6200,9189,10286"; a="256078338" X-IronPort-AV: E=Sophos;i="5.90,181,1643702400"; d="scan'208";a="256078338" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Mar 2022 12:19:28 -0700 X-IronPort-AV: E=Sophos;i="5.90,181,1643702400"; d="scan'208";a="515572133" Received: from zborja-mobl1.amr.corp.intel.com (HELO [10.212.239.199]) ([10.212.239.199]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Mar 2022 12:19:28 -0700 Message-ID: <40b468cb-5144-77f0-963a-67e81d2e3aa4@intel.com> Date: Mon, 14 Mar 2022 12:19:21 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Content-Language: en-US To: Kohei Tarumizu , catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20220311101940.3403607-1-tarumizu.kohei@fujitsu.com> From: Dave Hansen Subject: Re: [PATCH v2 0/8] Add hardware prefetch control driver for arm64 and x86 In-Reply-To: <20220311101940.3403607-1-tarumizu.kohei@fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/11/22 02:19, Kohei Tarumizu wrote: > The advantage of using this is improved performance. As an example of > performance improvements, the results of running the Stream benchmark > on the A64FX are described in section [Merit]. I take it that there are users out there today that are sufficiently motivated by the increased performance that they just do "wrmsr 0x1a4 0x1234". You talked about this in the "[Merit]" section. But, that's a _little_ unconvincing. I don't doubt that there is *a* workload out there that can benefit from hardware prefetcher tweaks. Do we really expect end users to run their workloads and tweak these values to find something optimal for them?