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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 6D089C2B9F7 for ; Wed, 26 May 2021 08:33:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43F6F613BC for ; Wed, 26 May 2021 08:33:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231519AbhEZIex (ORCPT ); Wed, 26 May 2021 04:34:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232166AbhEZIes (ORCPT ); Wed, 26 May 2021 04:34:48 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D904AC061574 for ; Wed, 26 May 2021 01:33:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Ayi1aZxpImaUKGH6duzMtDP6l99UaS5sywY/3DasNpU=; b=qh9DODudqPXQIY8M6srRqx+hlI BVH0SAG11gAaZJpweQoBW8mHLczvQwdN5BmIhMEw0RqptBpYv9dQeW/BQcTgiUWJ4iHYiUirk3jfD DcMzKRTZJDE1fNyngOaSpT4pY97kT5tKp9I0/R3R/mCAairZXC2fFt27xeKwAFOWjx8MtNp3rwM0+ SmLHX1wrjAibiX1VYsYpcPBkgvxA9tKQ4HlwFNQ5EYhT5a/d8RLRLtFbAEk08VRLS0V0hc0KoKDRo NYTrlqQu+xrUf3VIWg4vynNiSxX23Olp0DYfLA+h3i0HTFGKB7xPkRlZKFFyxCEZjgt8YkREcKUTv lww1wgUQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1lloxr-000Wkb-SA; Wed, 26 May 2021 08:32:39 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4B214300242; Wed, 26 May 2021 10:32:36 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0522C201DB6C5; Wed, 26 May 2021 10:32:36 +0200 (CEST) Date: Wed, 26 May 2021 10:32:35 +0200 From: Peter Zijlstra To: kajoljain Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, maddy@linux.vnet.ibm.com, santosh@fossix.org, aneesh.kumar@linux.ibm.com, vaibhav@linux.ibm.com, dan.j.williams@intel.com, ira.weiny@intel.com, atrajeev@linux.vnet.ibm.com, tglx@linutronix.de, rnsastry@linux.ibm.com Subject: Re: [RFC v2 4/4] powerpc/papr_scm: Add cpu hotplug support for nvdimm pmu device Message-ID: References: <20210525132216.1239259-1-kjain@linux.ibm.com> <20210525132216.1239259-5-kjain@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 26, 2021 at 12:56:58PM +0530, kajoljain wrote: > On 5/25/21 7:46 PM, Peter Zijlstra wrote: > > On Tue, May 25, 2021 at 06:52:16PM +0530, Kajol Jain wrote: > >> It adds cpumask to designate a cpu to make HCALL to > >> collect the counter data for the nvdimm device and > >> update ABI documentation accordingly. > >> > >> Result in power9 lpar system: > >> command:# cat /sys/devices/nmem0/cpumask > >> 0 > > > > Is this specific to the papr thing, or should this be in generic nvdimm > > code? > > This code is not specific to papr device and we can move it to > generic nvdimm interface. But do we need to add some checks on whether > any arch/platform specific driver want that support or we can assume > that this will be something needed by all platforms? I'm a complete NVDIMM n00b, but to me it would appear they would have to conform to the normal memory hierarchy and would thus always be per-node. Also, if/when deviation from this rule is observed, we can always rework/extend this. For now I think it would make sense to have the per-node ness of the thing expressed in the generic layer.