From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f41.google.com (mail-pa0-f41.google.com [209.85.220.41]) by kanga.kvack.org (Postfix) with ESMTP id DBA136B0069 for ; Thu, 27 Nov 2014 01:09:01 -0500 (EST) Received: by mail-pa0-f41.google.com with SMTP id rd3so4396585pab.0 for ; Wed, 26 Nov 2014 22:09:01 -0800 (PST) Received: from lgeamrelo01.lge.com (lgeamrelo01.lge.com. [156.147.1.125]) by mx.google.com with ESMTP id kv12si9870491pab.232.2014.11.26.22.08.58 for ; Wed, 26 Nov 2014 22:09:00 -0800 (PST) Date: Thu, 27 Nov 2014 15:12:04 +0900 From: Joonsoo Kim Subject: Re: [LSF/MM TOPIC] Improving CMA Message-ID: <20141127061204.GA6850@js1304-P5Q-DELUXE> References: <5473E146.7000503@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5473E146.7000503@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: Laura Abbott Cc: lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, zhuhui@xiaomi.com, minchan@kernel.org, gioh.kim@lge.com, SeongJae Park , mgorman@suse.de On Mon, Nov 24, 2014 at 05:54:14PM -0800, Laura Abbott wrote: > There have been a number of patch series posted designed to improve various > aspects of CMA. A sampling: > > https://lkml.org/lkml/2014/10/15/623 > http://marc.info/?l=linux-mm&m=141571797202006&w=2 > https://lkml.org/lkml/2014/6/26/549 > > As far as I can tell, these are all trying to fix real problems with CMA but > none of them have moved forward very much from what I can tell. The goal of > this session would be to come out with an agreement on what are the biggest > problems with CMA and the best ways to solve them. I also tried to solve problem from CMA, that is, reserved memory utilization. https://lkml.org/lkml/2014/5/28/64 While playing that patchset, I found serious problem about free page counting, so I stopped to develop it for a while and tried to fix it. Now, it is fixed by me and I can continue my patchset. https://lkml.org/lkml/2014/10/31/69 I heard that Minchan suggests new CMA zone like movable zone, and, I think that it would be the way to go. But, it would be a long-term goal and I'd like to solve utilization problem with my patchset for now. It is the biggest issue and it already forces someone to develop out of tree solution. It's not good that out of tree solution is used more and more in the product so I'd like to fix it quickly at first stage. I think that CMA have big potential. If we fix problems of CMA completely, it can be used for many places. One such case in my mind is hugetlb or THP. Until now, hugetlb uses reserved approach, that is very inefficient. System administrator carefully set the number of reserved hugepage according to whole system workload. And application can't use it freely, because it is very limited and managed resource. If we use CMA for hugetlb, we can easily allocate hugepage and application can use hugepages more freely. Anyway, I'd like to attend LSF/MM and discuss this topic. Thanks. -- 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