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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 93118C282CA for ; Tue, 12 Feb 2019 08:11:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3E8E22186A for ; Tue, 12 Feb 2019 08:11:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728399AbfBLILY (ORCPT ); Tue, 12 Feb 2019 03:11:24 -0500 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:37339 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727784AbfBLILY (ORCPT ); Tue, 12 Feb 2019 03:11:24 -0500 X-IronPort-AV: E=Sophos;i="5.58,361,1544482800"; d="scan'208";a="369024966" Received: from unknown (HELO [193.50.110.170]) ([193.50.110.170]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/AES128-SHA; 12 Feb 2019 09:11:04 +0100 Subject: Re: [PATCHv4 10/13] node: Add memory caching attributes To: Keith Busch , Jonathan Cameron Cc: "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "linux-mm@kvack.org" , Greg Kroah-Hartman , Rafael Wysocki , "Hansen, Dave" , "Williams, Dan J" References: <20190116175804.30196-1-keith.busch@intel.com> <20190116175804.30196-11-keith.busch@intel.com> <4a7d1c0c-c269-d7b2-11cb-88ad62b70a06@inria.fr> <20190210171958.00003ab2@huawei.com> <20190211152303.GA4525@localhost.localdomain> From: Brice Goglin Openpgp: preference=signencrypt Autocrypt: addr=Brice.Goglin@inria.fr; prefer-encrypt=mutual; keydata= mQINBFNg91oBEADMfOyfz9iilNPe1Yy3pheXLf5O/Vpr+gFJoXcjA80bMeSWBf4on8Mt5Fg/ jpVuNBhii0Zyq4Lip1I2ve+WQjfL3ixYQqvNRLgfw/FL0gNHSOe9dVFo0ol0lT+vu3AXOVmh AM4IrsOp2Tmt+w89Oyvu+xwHW54CJX3kXp4c7COz79A6OhbMEPQUreerTavSvYpH5pLY55WX qOSdjmlXD45yobQbMg9rFBy1BECrj4DJSpym/zJMFVnyC5yAq2RdPFRyvYfS0c491adD/iw9 eFZY1XWj+WqLSW8zEejdl78npWOucfin7eAKvov5Bqa1MLGS/2ojVMHXJN0qpStpKcueV5Px igX8i4O4pPT10xCXZ7R6KIGUe1FE0N7MLErLvBF6AjMyiFHix9rBG0pWADgCQUUFjc8YBKng nwIKl39uSpk5W5rXbZ9nF3Gp/uigTBNVvaLO4PIDw9J3svHQwCB31COsUWS1QhoLMIQPdUkk GarScanm8i37Ut9G+nB4nLeDRYpPIVBFXFD/DROIEfLqOXNbGwOjDd5RWuzA0TNzJSeOkH/0 qYr3gywjiE81zALO3UeDj8TaPAv3Dmu7SoI86Bl7qm6UOnSL7KQxZWuMTlU3BF3d+0Ly0qxv k1XRPrL58IyoHIgAVom0uUnLkRKHczdhGDpNzsQDJaO71EPp8QARAQABtCRCcmljZSBHb2ds aW4gPEJyaWNlLkdvZ2xpbkBpbnJpYS5mcj6JAjgEEwECACIFAlNg+aMCGwMGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAAAoJEESRkPMjWr076RoQAJhJ1q5+wlHIf+YvM0N1V1hQyf+aL35+ BPqxlyw4H65eMWIN/63yWhcxrLwNCdgY1WDWGoiW8KVCCHwJAmrXukFvXjsvShLQJavWRgKH eea12T9XtLc6qY/DEi2/rZvjOCKsMjnc1CYW71jbofaQP6lJsmC+RPWrnL/kjZyVrVrg7/Jo GemLmi/Ny7nLAOt6uL0MC/Mwld14Yud57Qz6VTDGSOvpNacbkJtcCwL3KZDBfSDnZtSbeclY srXoMnFXEJJjKJ6kcJrZDYPrNPkgFpSId/WKJ5pZBoRsKH/w2OdxwtXKCYHksMCiI4+4fVFD WlmVNYzW8ZKXjAstLh+xGABkLVXs+0WjvC67iTZBXTmbYJ5eodv8U0dCIR/dxjK9wxVKbIr2 D+UVbGlfqUuh1zzL68YsOg3L0Xc6TQglKVl6RxX87fCU8ycIs9pMbXeRDoJohflo8NUDpljm zqGlZxBjvb40p37ReJ+VfjWqAvVh+6JLaMpeva/2K1Nvr9O/DOkSRNetrd86PslrIwz8yP4l FaeG0dUwdRdnToNz6E8lbTVOwximW+nwEqOZUs1pQNKDejruN7Xnorr7wVBfp6zZmFCcmlw9 8pSMV3p85wg6nqJnBkQNTzlljycBvZLVvqc6hPOSXpXf5tjkuUVWgtbCc8TDEQFx8Phkgda6 K1LNuQINBFNg91oBEADp3vwjw8tQBnNfYJNJMs6AXC8PXB5uApT1pJ0fioaXvifPNL6gzsGt AF53aLeqB7UXuByHr8Bmsz7BvwA06XfXXdyLQP+8Oz3ZnUpw5inDIzLpRbUuAjI+IjUtguIK AkU1rZNdCXMOqEwCaomRitwaiX9H7yiDTKCUaqx8yAuAQWactWDdyFii2FA7IwVlD/GBqMWV weZsMfeWgPumKB3jyElm1RpkzULrtKbu7MToMH2fmWqBtTkRptABkY7VEd8qENKJBZKJGisk Fk6ylp8VzZdwbAtEDDTGK00Vg4PZGiIGbQo8mBqbc63DY+MdyUEksTTu2gTcqZMm/unQUJA8 xB4JrTAyljo/peIt6lsQa4+/eVolfKL1t1C3DY8f4wMoqnZORagnWA2oHsLsYKvcnqzA0QtY IIb1S1YatV+MNMFf3HuN7xr/jWlfdt59quXiOHU3qxIzXJo/OfC3mwNW4zQWJkG233UOf6YE rmrSaTIBTIWF8CxGY9iXPaJGNYSUa6R/VJS09EWeZgRz9Gk3h5AyDrdo5RFN9HNwOj41o0cj eLDF69092Lg5p5isuOqsrlPi5imHKcDtrXS7LacUI6H0c8onWoH9LuW99WznEtFgPJg++TAv f9M2x57Gzl+/nYTB5/Kpl1qdPPC91zUipiKbnF5f8bQpol0WC+ovmQARAQABiQIfBBgBAgAJ BQJTYPdaAhsMAAoJEESRkPMjWr074+0P/iEcN27dx3oBTzoeGEBhZUVQRZ7w4A61H/vW8oO8 IPkZv9kFr5pCfIonmHEbBlg6yfjeHXwF5SF2ywWRKkRsFHpaFWywxqk9HWXu8cGR1pFsrwC3 EdossuVbEFNmhjHvcAo11nJ7JFzPTEnlPjE6OY9tEDwl+kp1WvyXqNk9bosaX8ivikhmhB47 7BA3Kv8uUE7UL6p7CBdqumaOFISi1we5PYE4P/6YcyhQ9Z2wH6ad2PpwAFNBwxSu+xCrVmaD skAwknf6UVPN3bt67sFAaVgotepx6SPhBuH4OSOxVHMDDLMu7W7pJjnSKzMcAyXmdjON05Sz SaILwfceByvHAnvcFh2pXK9U4E/SyWZDJEcGRRt79akzZxls52stJK/2Tsr0vKtZVAwogiaK uSp+m6BRQcVVhTo/Kq3E0tSnsTHFeIO6QFHKJCJv4FRE3Dmtz15lueihUBowsq9Hk+u3UiLo SmrMAZ6KgA4SQxB2p8/M53kNJl92HHc9nc//aCQDi1R71NyhtSx+6PyivoBkuaKYs+S4pHmt sFE+5+pkUNROtm4ExLen4N4OL6Kq85mWGf2f6hd+OWtn8we1mADjDtdnDHuv+3E3cacFJPP/ wFV94ZhqvW4QcyBWcRNFA5roa7vcnu/MsCcBoheR0UdYsOnJoEpSZswvC/BGqJTkA2sf Message-ID: <854e892c-0c0d-6ab8-bc83-3c6b462bcf72@inria.fr> Date: Tue, 12 Feb 2019 09:11:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190211152303.GA4525@localhost.localdomain> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 11/02/2019 à 16:23, Keith Busch a écrit : > On Sun, Feb 10, 2019 at 09:19:58AM -0800, Jonathan Cameron wrote: >> On Sat, 9 Feb 2019 09:20:53 +0100 >> Brice Goglin wrote: >> >>> Hello Keith >>> >>> Could we ever have a single side cache in front of two NUMA nodes ? I >>> don't see a way to find that out in the current implementation. Would we >>> have an "id" and/or "nodemap" bitmask in the sidecache structure ? >> This is certainly a possible thing for hardware to do. >> >> ACPI IIRC doesn't provide any means of representing that - your best >> option is to represent it as two different entries, one for each of the >> memory nodes. Interesting question of whether you would then claim >> they were half as big each, or the full size. Of course, there are >> other possible ways to get this info beyond HMAT, so perhaps the interface >> should allow it to be exposed if available? > HMAT doesn't do this, but I want this interface abstracted enough from > HMAT to express whatever is necessary. > > The CPU cache is the closest existing exported attributes to this, > and they provide "shared_cpu_list". To that end, I can export a > "shared_node_list", though previous reviews strongly disliked multi-value > sysfs entries. :( > > Would shared-node symlinks capture the need, and more acceptable? As a user-space guy reading these files/symlinks, I would prefer reading a bitmask just like we do for CPU cache "cpumap" or CPU "siblings" files (or sibling_list). Reading a directory and looking for dentries matching "foo%d" is far less convenient  in C. If all these files are inside a dedicated subdirectory, it's better but still not as easy. Brice