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 09:19:50 +0900 Message-ID: <559C6CA6.1050809@lge.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20150707170746.1b91ba0d07382cbc9ba3db92@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.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 9:07=EC=97=90 Andrew Morton =EC=9D=B4(=EA= =B0=80) =EC=93=B4 =EA=B8=80: > 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 wrot= e: >>> >>>> From: Gioh Kim >>>> >>>> Hello, >>>> >>>> This series try to enable migration of non-LRU pages, such as driv= er's page. >>>> >>>> My ARM-based platform occured severe fragmentation problem after l= ong-term >>>> (several days) test. Sometimes even order-3 page allocation failed= =2E It has >>>> memory size 512MB ~ 1024MB. 30% ~ 40% memory is consumed for graph= ic processing >>>> and 20~30 memory is reserved for zram. >>>> >>>> I found that many pages of GPU driver and zram are non-movable pag= es. So I >>>> reported Minchan Kim, the maintainer of zram, and he made the inte= rnal >>>> compaction logic of zram. And I made the internal compaction of GP= U driver. >>>> >>>> They reduced some fragmentation but they are not enough effective. >>>> They are activated by its own interface, /sys, so they are not coo= perative >>>> with kernel compaction. If there is too much fragmentation and ker= nel starts >>>> to compaction, zram and GPU driver cannot work with the kernel com= paction. >>>> >>>> ... >>>> >>>> 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 co= mmand >>>> - 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 ker= nel source, >> for kernel developers' undestanding. So I selected the balloon drive= r >> because it has already compaction and working with kernel compaction= =2E >> I can show how driver pages is compacted with lru-pages together. >> >> Actually balloon driver is not best example to show how this patch c= ompacts pages. >> The balloon driver compaction is decreasing page consumtion, for ins= tance 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, wiri= ng > 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 pat= ch them. It's too bad. Minchan Kim said he had a plan to apply this patch into zram compaction= =2E Many embedded machines use several hundreds MB for zram. The zram can also have benefit with this patch as much as GPU drivers. > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kerne= l" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >