Re: [PATCH v5 0/4] mm/page_reporting: Make page reporting work on arm64 with 64KB page size

[Gavin Shan]

On 6/25/21 3:58 PM, Michael S. Tsirkin wrote:
> On Fri, Jun 25, 2021 at 12:21:46PM +0800, Gavin Shan wrote:
> > 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

> > 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