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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 47017C32771 for ; Mon, 27 Jan 2020 09:23:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 18E3B2071E for ; Mon, 27 Jan 2020 09:23:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580117020; bh=R5F3gDdinhWx9PXifVa0BK+glPUoqZnwwsu/mEApxOU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=zbqZW5k++q2AJAyqODSOKXKIOtEkFAhiSJA7XqZjy92SUeANkW9XZoKt2dETsFWln WUjYjHFHWsNu7oneh+jv6a26Kd4pOkXBmP2qcMqxXjhWbeTsZGDouCO/2acSIu/9au QaDAGA7oGIeBAdrU3slmb4v4byQIt4ckLsdm3Gmg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729211AbgA0JXj (ORCPT ); Mon, 27 Jan 2020 04:23:39 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:41856 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729309AbgA0JXj (ORCPT ); Mon, 27 Jan 2020 04:23:39 -0500 Received: by mail-wr1-f67.google.com with SMTP id c9so10233949wrw.8; Mon, 27 Jan 2020 01:23:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=iB179YEXMH0Yt0ro4mYymZKjwvAi7/XXsGDXQ0hTWsI=; b=VWSrV4y/9wy3WrU/Azy97yOGDoWlnH3h4/V9xIeTuh3cX/UTGRZqnG+rd3GIyovyCU +PBM/Sz3P5hBcbGNOKn7mIJBslhLV9i4rDsXTM41icEiygicm+51wccT+DjyX8v9gpHY vHMtlcjzeGGnCGzd7UcFx0YV7oz6RzyVo3rDjsk0f/zO86vPjotPDIM/xRlEjBNfC/TE /Fa0S8FZwsTVgMVNF4EazsiVIqAEOJVIFaFTSYPgueM5L/CBGClzzkTrtwPzCMRkCDnZ gw6NMzw9LdOLcoLgLtfBN2ZOSUCNZL1PyhJx+It/Tzcpro3FTVAHMca5cfJhVF7+aKcK Lq7g== X-Gm-Message-State: APjAAAWY7g3WfhmZFOUUVKG+AjM/KLNuzsUMxqz993osXigPo2dWN7Eb a/LwcJ4k0rW4wiFw8oJWZ24= X-Google-Smtp-Source: APXvYqxBL2+UZXYovhxnLlgmNuemevZWEkeU9+AkHbPfVxM5zIbKMiTMST3nLI2PnOgVNp/EGaWouA== X-Received: by 2002:a05:6000:1052:: with SMTP id c18mr20075996wrx.268.1580117017259; Mon, 27 Jan 2020 01:23:37 -0800 (PST) Received: from localhost (prg-ext-pat.suse.com. [213.151.95.130]) by smtp.gmail.com with ESMTPSA id m10sm20048223wrx.19.2020.01.27.01.23.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jan 2020 01:23:36 -0800 (PST) Date: Mon, 27 Jan 2020 10:23:34 +0100 From: Michal Hocko To: "Fontenot, Nathan" Cc: David Hildenbrand , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dan Williams , Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , powerpc-utils-devel@googlegroups.com, util-linux@vger.kernel.org, Badari Pulavarty , Robert Jennings , Heiko Carstens , Karel Zak Subject: Re: [PATCH RFC] drivers/base/memory.c: indicate all memory blocks as removable Message-ID: <20200127092334.GB1183@dhcp22.suse.cz> References: <20200124155336.17126-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: util-linux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: util-linux@vger.kernel.org On Fri 24-01-20 13:10:22, Fontenot, Nathan wrote: > It's been awhile since I've looked at the powerpc-utils drmgr command and > pseries DLPAR code but a quick scan makes and it appears that it hasn't changed > too much. Given that, some thoughts. > > The sysfs 'removable' file was a great help when memory DLPAR was driven > from userspace in the powerpc-utils drmgr command. Having this check did improve > performance though I can't point to any numbers. Do you still have an access to the HW to give it a try? > Currently, memory DLPAR is done completely in the kernel. The request is > initiated from drmgr writing to /sys/kernel/dlpar (for pHyp partitions) > or from a hotplug interrupt (for guests). I don't believe the 'removable' > sysfs file is used in either of these paths by drmgr. The only time it is > used is on older kernels that do not support in-kernel memory DLPAR. > > Given this, I don't think removing the 'removable' sysfs file would cause any > issues for the drmgr command. The only scenario I can think of is using an old > version of drmgr that does not support in-kernel memory DLPAR on a new kernel > where the 'removable' sysfs file has been removed. This doesn't seem likely > though and drmgr could be updated to detect this. Thanks for the information! -- Michal Hocko SUSE Labs