2015-07-13 오후 6:24에 Konstantin Khlebnikov 이(가) 쓴 글:
On Mon, Jul 13, 2015 at 11:35 AM, 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.
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@xxxxxxxxx>
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.
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