On Wed, Jul 08, 2015 at 09:19:50AM +0900, Gioh Kim wrote: > > > 2015-07-08 오전 9:07에 Andrew Morton 이(가) 쓴 글: > >On Wed, 08 Jul 2015 09:02:59 +0900 Gioh Kim <gioh.kim@xxxxxxx> wrote: > > > >> > >> > >>2015-07-08 ______ 7:37___ Andrew Morton ___(___) ___ ___: > >>>On Tue, 7 Jul 2015 13:36:20 +0900 Gioh Kim <gioh.kim@xxxxxxx> wrote: > >>> > >>>>From: Gioh Kim <gurugio@xxxxxxxxxxx> > >>>> > >>>>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 from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
