[PATCH 0/4] enable migration of driver pages

Gioh Kim
Mon, 13 Jul 2015 10:02:28 -0000

2015-07-13 ?? 6:24? Konstantin Khlebnikov ?(?) ? ?:
> On Mon, Jul 13, 2015 at 11:35 AM, Gioh Kim <gioh.kim at lge.com>
wrote:
>> From: Gioh Kim <gurugio at hanmail.net>
>>
>> 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.
>>
>> So I thought there needs a interface to combine driver and kernel
compaction.
>> This patch adds a generic isolate/migrate/putback callbacks for page
>> address-space and a new interface to create anon-inode to manage
>> address_space_operation. The zram and GPU, and any other modules can
create
>> anon_inode and register its own migration method. The kernel compaction
can
>> call the registered migration when it does compaction.
>>
>> My GPU driver source is not in-kernel driver so that I apply the
interface
>> into balloon driver. The balloon driver is already merged
>> into the kernel compaction as a corner-case. This patch have the
balloon
>> driver migration be called by the generic interface.
>>
>>
>> This patch set combines 4 patches.
>>
>> 1. patch 1/4: get inode from anon_inodes
>> This patch adds new interface to create inode from anon_inodes.
>>
>> 2. patch 2/4: framework to isolate/migrate/putback page
>> Add isolatepage, putbackpage into address_space_operations
>> and wrapper function to call them.
>>
>> 3. patch 3/4: apply the framework into balloon driver
>> The balloon driver is applied into the framework. It gets a inode
>> from anon_inodes and register operations in the inode.
>> The kernel compaction calls generic interfaces, not balloon
>> driver interfaces.
>> Any other drivers can register operations via inode like this
>> to migrate it's pages.
>>
>> 4. patch 4/4: remove direct calling of migration of driver pages
>> Non-lru pages are also migrated with lru pages by move_to_new_page().
>
> The whole patchset looks good.
>
> Reviewed-by: Konstantin Khlebnikov <koct9i at gmail.com>
>
>>
>> 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
>
> Another simple test is several instances of
> tools/testing/selftests/vm/transhuge-stress.c
> runnng in parallel with balloon inflating/deflating.
> (transparent huge pages must be enabled of course)
> That catched a lot of races in ballooning code.
>

Great!
I'll do it and inform you the result in this week.