On 6/25/21 3:58 PM, Michael S. Tsirkin wrote:

On Fri, Jun 25, 2021 at 12:21:46PM +0800, Gavin Shan wrote:

quoted

The page reporting threshold is currently equal to @pageblock_order, which
is 13 and 512MB on arm64 with 64KB base page size selected. The page
reporting won't be triggered if the freeing page can't come up with a free
area like that huge. The condition is hard to be met, especially when the
system memory becomes fragmented.

This series intends to solve the issue by having page reporting threshold
as 5 (2MB) on arm64 with 64KB base page size. The patches are organized as:

    PATCH[1/4] Fix some coding style in __page_reporting_request().
    PATCH[2/4] Represents page reporting order with variable so that it can
               be exported as module parameter.
    PATCH[3/4] Allows the device driver (e.g. virtio_balloon) to specify
               the page reporting order when the device info is registered.
    PATCH[4/4] Specifies the page reporting order to 5, corresponding to
               2MB in size on ARM64 when 64KB base page size is used.

I sent comments on v4. They still apply I think. Want me to repeat them
here?

Thanks for your comments, Michael. I've replied to your comments
through v4. There are some future work as Alex and David pointed
out before: In order to remove the hack in virtio-memballoon, the
VMM needs to report the page reporting order. I will keep working
on this when I have spare time.

Thanks,
Gavin

quoted

Changelog
=========
v5:
    * Restore @page_reporting_order to @pageblock_order when
      device is registered in PATCH[2/4] to keep "git bisect"
      friendly at least.                                           (Alex)
v4:
    * Set @page_reporting_order to MAX_ORDER. Its value is
      specified by the driver or falls back to @pageblock_order
      when page reporting device is registered.                    (Alex)
    * Include "module.h" in page_reporting.c                       (Andrew)
v3:
    * Avoid overhead introduced by function all                    (Alex)
    * Export page reporting order as module parameter              (Gavin)
v2:
    * Rewrite the patches as Alex suggested                        (Alex)

Gavin Shan (4):
   mm/page_reporting: Fix code style in __page_reporting_request()
   mm/page_reporting: Export reporting order as module parameter
   mm/page_reporting: Allow driver to specify reporting
   virtio_balloon: Specify page reporting order if needed

  .../admin-guide/kernel-parameters.txt         |  6 +++++
  drivers/virtio/virtio_balloon.c               | 17 ++++++++++++++
  include/linux/page_reporting.h                |  3 +++
  mm/page_reporting.c                           | 22 +++++++++++++++----
  mm/page_reporting.h                           |  5 ++---
  5 files changed, 46 insertions(+), 7 deletions(-)

-- 
2.23.0