From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941131AbcIUTWG (ORCPT ); Wed, 21 Sep 2016 15:22:06 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:33192 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933187AbcIUTWE (ORCPT ); Wed, 21 Sep 2016 15:22:04 -0400 Date: Wed, 21 Sep 2016 21:22:01 +0200 From: Michal Hocko To: Dave Hansen Cc: Mike Kravetz , Gerald Schaefer , Andrew Morton , Naoya Horiguchi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" , Vlastimil Babka , "Aneesh Kumar K . V" , Martin Schwidefsky , Heiko Carstens , Rui Teng Subject: Re: [PATCH 0/1] memory offline issues with hugepage size > memory block size Message-ID: <20160921192201.GL24210@dhcp22.suse.cz> References: <20160920155354.54403-1-gerald.schaefer@de.ibm.com> <20160921182054.GK24210@dhcp22.suse.cz> <57E2D124.9000108@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57E2D124.9000108@linux.intel.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 21-09-16 11:27:48, Dave Hansen wrote: > On 09/21/2016 11:20 AM, Michal Hocko wrote: > > I would even question the per page block offlining itself. Why would > > anybody want to offline few blocks rather than the whole node? What is > > the usecase here? > > The original reason was so that you could remove a DIMM or a riser card > full of DIMMs, which are certainly a subset of a node. OK, I see, thanks for the clarification! I was always thinking more in node rather than physical memory range hot-remove. I do agree that it makes sense to free the whole gigantic huge page if we encounter a tail page for the above use case because losing the gigantic page is justified when the whole dim goes away. Thanks! -- Michal Hocko SUSE Labs