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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 F08AFC43441 for ; Mon, 26 Nov 2018 15:17:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C238E20664 for ; Mon, 26 Nov 2018 15:17:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C238E20664 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726470AbeK0CMS (ORCPT ); Mon, 26 Nov 2018 21:12:18 -0500 Received: from mga11.intel.com ([192.55.52.93]:46986 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726242AbeK0CMR (ORCPT ); Mon, 26 Nov 2018 21:12:17 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Nov 2018 07:17:49 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,282,1539673200"; d="scan'208";a="108598701" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by fmsmga002.fm.intel.com with ESMTP; 26 Nov 2018 07:17:48 -0800 Date: Mon, 26 Nov 2018 08:14:47 -0700 From: Keith Busch To: Anshuman Khandual Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , Rafael Wysocki , Dave Hansen , Dan Williams Subject: Re: [PATCH 4/7] node: Add memory caching attributes Message-ID: <20181126151446.GK26707@localhost.localdomain> References: <20181114224921.12123-2-keith.busch@intel.com> <20181114224921.12123-5-keith.busch@intel.com> <91698cef-cdcd-5143-884f-3da5536e156f@arm.com> <20181119230600.GC26707@localhost.localdomain> <731533d5-26e1-ade7-1a63-d1f85461d091@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <731533d5-26e1-ade7-1a63-d1f85461d091@arm.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 22, 2018 at 06:59:21PM +0530, Anshuman Khandual wrote: > > > On 11/20/2018 04:36 AM, Keith Busch wrote: > > On Mon, Nov 19, 2018 at 09:44:00AM +0530, Anshuman Khandual wrote: > >> On 11/15/2018 04:19 AM, Keith Busch wrote: > >>> System memory may have side caches to help improve access speed. While > >>> the system provided cache is transparent to the software accessing > >>> these memory ranges, applications can optimize their own access based > >>> on cache attributes. > >> > >> Cache is not a separate memory attribute. It impacts how the real attributes > >> like bandwidth, latency e.g which are already captured in the previous patch. > >> What is the purpose of adding this as a separate attribute ? Can you explain > >> how this is going to help the user space apart from the hints it has already > >> received with bandwidth, latency etc properties. > > > > I am not sure I understand the question here. Access bandwidth and latency > > are entirely attributes different than what this patch provides. If the > > system side-caches memory, the associativity, line size, and total size > > can optionally be used by software to improve performance. > > Okay but then does this belong to this series which about memory attributes ? This patch series is about exporting memory attributes, and this system memory caching is one such attribute, so yes, I think it belongs.