On Fri, 2019-12-13 at 02:08 -0500, Michael S. Tsirkin wrote: > On Thu, Dec 05, 2019 at 08:22:55AM -0800, Alexander Duyck wrote: > > From: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx> > > > > Add support for the page reporting feature provided by virtio-balloon. > > Reporting differs from the regular balloon functionality in that is is > > much less durable than a standard memory balloon. Instead of creating a > > list of pages that cannot be accessed the pages are only inaccessible > > while they are being indicated to the virtio interface. Once the > > interface has acknowledged them they are placed back into their respective > > free lists and are once again accessible by the guest system. > > > > Unlike a standard balloon we don't inflate and deflate the pages. Instead > > we perform the reporting, and once the reporting is completed it is > > assumed that the page has been dropped from the guest and will be faulted > > back in the next time the page is accessed. > > > > For this reason when I had originally introduced the patch set I referred > > to this behavior as a "bubble" instead of a "balloon" since the duration > > is short lived, and when the page is touched the "bubble" is popped and > > the page is faulted back in. > > > > Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx> > > virtio POV is fine here: > > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > However please copy virtio-comment on UAPI changes. So I have been avoiding copying virtio-dev on the kernel changes as I had gotten feedback that it was annoying some people as they were getting bounces since they were not subscribed. Will the same type of thing happen with virtio-comment? > If possible isolate the last chunk in a patch by itself > to make it easier for non-kernel developers to review. Are you talking about the change in "include/uapi/linux/virtio_balloon.h"? I have it as a standalone patch in the QEMU set, and for the QEMU set I had included virtio-dev. Would you prefer I include virtio-comment instead or in addition to virtio-dev? My thought is that I would prefer to keep the virtio people focused on the QEMU code since they are probably more comfortable with that, and the kernel people focused on the kernel code. > > --- > > drivers/virtio/Kconfig | 1 + > > drivers/virtio/virtio_balloon.c | 64 +++++++++++++++++++++++++++++++++++ > > include/uapi/linux/virtio_balloon.h | 1 + > > 3 files changed, 66 insertions(+) <snip> > > > > diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h > > index a1966cd7b677..19974392d324 100644 > > --- a/include/uapi/linux/virtio_balloon.h > > +++ b/include/uapi/linux/virtio_balloon.h > > @@ -36,6 +36,7 @@ > > #define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */ > > #define VIRTIO_BALLOON_F_FREE_PAGE_HINT 3 /* VQ to report free pages */ > > #define VIRTIO_BALLOON_F_PAGE_POISON 4 /* Guest is using page poisoning */ > > +#define VIRTIO_BALLOON_F_REPORTING 5 /* Page reporting virtqueue */ > > > > /* Size of a PFN in the balloon interface. */ > > #define VIRTIO_BALLOON_PFN_SHIFT 12 If this is the bit we are talking about I have it split out already into a QEMU specific patch as well, it can be found here: https://lore.kernel.org/lkml/20191205162422.19737.57728.stgit@localhost.localdomain/ If needed I could probably add a cover page and/or update the comments in that patch if that is needed to better explain the change. Thanks. - Alex
