From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gioh Kim Subject: Re: [RFCv3 0/5] enable migration of driver pages Date: Wed, 08 Jul 2015 09:02:59 +0900 Message-ID: <559C68B3.3010105@lge.com> References: <1436243785-24105-1-git-send-email-gioh.kim@lge.com> <20150707153701.bfcde75108d1fb8aaedc8134@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20150707153701.bfcde75108d1fb8aaedc8134@linux-foundation.org> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: jlayton@poochiereds.net, bfields@fieldses.org, vbabka@suse.cz, iamjoonsoo.kim@lge.com, viro@zeniv.linux.org.uk, mst@redhat.com, koct9i@gmail.com, minchan@kernel.org, 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 List-Id: linux-api@vger.kernel.org 2015-07-08 =EC=98=A4=EC=A0=84 7:37=EC=97=90 Andrew Morton =EC=9D=B4(=EA=B0= =80) =EC=93=B4 =EA=B8=80: > 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 p= rocessing >> 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 dr= iver. >> >> They reduced some fragmentation but they are not enough effective. >> They are activated by its own interface, /sys, so they are not coopera= tive >> with kernel compaction. If there is too much fragmentation and kernel = starts >> to compaction, zram and GPU driver cannot work with the kernel compact= ion. >> >> ... >> >> 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 comman= d >> - 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 co= mpact, the system can get free high-order pages. I have to show how this patch work with a driver existing in the kernel s= ource, 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 compac= ts 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. > > Why are your changes to the GPU driver not included in this patch serie= s? My platform is ARM-based and GPU is ARM-Mali. The driver is not open sour= ce. It's too bad that I cannot show effect of this patch with the GPU driver. > > > -- 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