Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753614AbdHQVzy (ORCPT ); Thu, 17 Aug 2017 17:55:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37488 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753470AbdHQVzw (ORCPT ); Thu, 17 Aug 2017 17:55:52 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com A496137E88 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jglisse@redhat.com Date: Thu, 17 Aug 2017 17:55:50 -0400 From: Jerome Glisse To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, John Hubbard , Dan Williams , David Nellans , Balbir Singh Subject: Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Message-ID: <20170817215549.GD2872@redhat.com> References: <20170817000548.32038-1-jglisse@redhat.com> <20170817143916.63fca76e4c1fd841e0afd4cf@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170817143916.63fca76e4c1fd841e0afd4cf@linux-foundation.org> User-Agent: Mutt/1.8.3 (2017-05-23) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Thu, 17 Aug 2017 21:55:52 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1004 Lines: 25 On Thu, Aug 17, 2017 at 02:39:16PM -0700, Andrew Morton wrote: > On Wed, 16 Aug 2017 20:05:29 -0400 J__r__me Glisse wrote: > > > Heterogeneous Memory Management (HMM) (description and justification) > > The patchset adds 55 kbytes to x86_64's mm/*.o and there doesn't appear > to be any way of avoiding this overhead, or of avoiding whatever > runtime overheads are added. HMM have already been integrated in couple of Red Hat kernel and AFAIK there is no runtime performance issue reported. Thought the RHEL version does not use static key as Dan asked. > > It also adds 18k to arm's mm/*.o and arm doesn't support HMM at all. > > So that's all quite a lot of bloat for systems which get no benefit from > the patchset. What can we do to improve this situation (a lot)? I will look into why object file grow so much on arm. My guess is that the new migrate code is the bulk of that. I can hide the new page migration code behind a kernel configuration flag. Cheers, J?r?me