From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f49.google.com (mail-pa0-f49.google.com [209.85.220.49]) by kanga.kvack.org (Postfix) with ESMTP id 8166F6B0038 for ; Tue, 7 Jul 2015 20:35:21 -0400 (EDT) Received: by pacws9 with SMTP id ws9so122812515pac.0 for ; Tue, 07 Jul 2015 17:35:21 -0700 (PDT) Received: from mail-pd0-x22e.google.com (mail-pd0-x22e.google.com. [2607:f8b0:400e:c02::22e]) by mx.google.com with ESMTPS id kn8si857755pab.45.2015.07.07.17.35.20 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Jul 2015 17:35:20 -0700 (PDT) Received: by pddu5 with SMTP id u5so47214508pdd.3 for ; Tue, 07 Jul 2015 17:35:20 -0700 (PDT) Date: Wed, 8 Jul 2015 09:35:08 +0900 From: Minchan Kim Subject: Re: [RFCv3 0/5] enable migration of driver pages Message-ID: <20150708003507.GA8764@blaptop.AC68U> References: <1436243785-24105-1-git-send-email-gioh.kim@lge.com> <20150707153701.bfcde75108d1fb8aaedc8134@linux-foundation.org> <559C68B3.3010105@lge.com> <20150707170746.1b91ba0d07382cbc9ba3db92@linux-foundation.org> <559C6CA6.1050809@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <559C6CA6.1050809@lge.com> Sender: owner-linux-mm@kvack.org List-ID: To: Gioh Kim Cc: Andrew Morton , jlayton@poochiereds.net, bfields@fieldses.org, vbabka@suse.cz, iamjoonsoo.kim@lge.com, viro@zeniv.linux.org.uk, mst@redhat.com, koct9i@gmail.com, aquini@redhat.com, linux-fsdevel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-mm@kvack.org, gunho.lee@lge.com, Gioh Kim On Wed, Jul 08, 2015 at 09:19:50AM +0900, Gioh Kim wrote: > > > 2015-07-08 i??i ? 9:07i?? Andrew Morton i?'(e??) i?' e,?: > >On Wed, 08 Jul 2015 09:02:59 +0900 Gioh Kim wrote: > > > >> > >> > >>2015-07-08 ______ 7:37___ Andrew Morton ___(___) ___ ___: > >>>On Tue, 7 Jul 2015 13:36:20 +0900 Gioh Kim wrote: > >>> > >>>>From: Gioh Kim > >>>> > >>>>Hello, > >>>> > >>>>This series try to enable migration of non-LRU pages, such as driver's page. > >>>> > >>>>My ARM-based platform occured severe fragmentation problem after long-term > >>>>(several days) test. Sometimes even order-3 page allocation failed. It has > >>>>memory size 512MB ~ 1024MB. 30% ~ 40% memory is consumed for graphic processing > >>>>and 20~30 memory is reserved for zram. > >>>> > >>>>I found that many pages of GPU driver and zram are non-movable pages. So I > >>>>reported Minchan Kim, the maintainer of zram, and he made the internal > >>>>compaction logic of zram. And I made the internal compaction of GPU driver. > >>>> > >>>>They reduced some fragmentation but they are not enough effective. > >>>>They are activated by its own interface, /sys, so they are not cooperative > >>>>with kernel compaction. If there is too much fragmentation and kernel starts > >>>>to compaction, zram and GPU driver cannot work with the kernel compaction. > >>>> > >>>>... > >>>> > >>>>This patch set is tested: > >>>>- turn on Ubuntu 14.04 with 1G memory on qemu. > >>>>- do kernel building > >>>>- after several seconds check more than 512MB is used with free command > >>>>- command "balloon 512" in qemu monitor > >>>>- check hundreds MB of pages are migrated > >>> > >>>OK, but what happens if the balloon driver is not used to force > >>>compaction? Does your test machine successfully compact pages on > >>>demand, so those order-3 allocations now succeed? > >> > >>If any driver that has many pages like the balloon driver is forced to compact, > >>the system can get free high-order pages. > >> > >>I have to show how this patch work with a driver existing in the kernel source, > >>for kernel developers' undestanding. So I selected the balloon driver > >>because it has already compaction and working with kernel compaction. > >>I can show how driver pages is compacted with lru-pages together. > >> > >>Actually balloon driver is not best example to show how this patch compacts pages. > >>The balloon driver compaction is decreasing page consumtion, for instance 1024MB -> 512MB. > >>I think it is not compaction precisely. It frees pages. > >>Of course there will be many high-order pages after 512MB is freed. > > > >Can the various in-kernel GPU drivers benefit from this? If so, wiring > >up one or more of those would be helpful? > > I'm sure that other in-kernel GPU drivers can have benefit. > It must be helpful. > > If I was familiar with other in-kernel GPU drivers code, I tried to patch them. > It's too bad. > > Minchan Kim said he had a plan to apply this patch into zram compaction. > Many embedded machines use several hundreds MB for zram. > The zram can also have benefit with this patch as much as GPU drivers. > Hello Gioh, It would be helpful for fork-latency and zra+CMA in small memory system. I will implement zsmalloc.migratepages after I finish current going works. Thanks for the nice work! -- Kind regards, Minchan Kim -- 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