From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f198.google.com (mail-yw0-f198.google.com [209.85.161.198]) by kanga.kvack.org (Postfix) with ESMTP id 4D6BC6B025F for ; Thu, 17 Aug 2017 17:59:22 -0400 (EDT) Received: by mail-yw0-f198.google.com with SMTP id g75so128064919ywb.0 for ; Thu, 17 Aug 2017 14:59:22 -0700 (PDT) Received: from mail-yw0-x232.google.com (mail-yw0-x232.google.com. [2607:f8b0:4002:c05::232]) by mx.google.com with ESMTPS id r143si855093ywg.348.2017.08.17.14.59.21 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Aug 2017 14:59:21 -0700 (PDT) Received: by mail-yw0-x232.google.com with SMTP id u207so49194642ywc.3 for ; Thu, 17 Aug 2017 14:59:21 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170817215549.GD2872@redhat.com> References: <20170817000548.32038-1-jglisse@redhat.com> <20170817143916.63fca76e4c1fd841e0afd4cf@linux-foundation.org> <20170817215549.GD2872@redhat.com> From: Dan Williams Date: Thu, 17 Aug 2017 14:59:20 -0700 Message-ID: Subject: Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Jerome Glisse Cc: Andrew Morton , "linux-kernel@vger.kernel.org" , Linux MM , John Hubbard , David Nellans , Balbir Singh On Thu, Aug 17, 2017 at 2:55 PM, Jerome Glisse wrote: > 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. Shouldn't we completely disable all of it unless there is a driver in the kernel that selects it? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org