This series provides an asynchronous means of reporting free guest pages to QEMU through virtio-balloon so that the memory associated with those pages can be dropped and reused by other processes and/or guests on the host. Using this it is possible to avoid unnecessary I/O to disk and greatly improve performance in the case of memory overcommit on the host.
I originally submitted this patch series back on February 11th 2020[1], but at that time I was focused primarily on the kernel portion of this patch set. However as of April 7th those patches are now included in Linus's kernel tree[2] and so I am submitting the QEMU pieces for inclusion. [1]: https://lore.kernel.org/lkml/20200211224416.29318.44077.stgit@localhost.localdomain/ [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b0c504f154718904ae49349147e3b7e6ae91ffdc Changes from v17: Fixed typo in patch 1 title Addressed white-space issues reported via checkpatch Added braces {} for two if statements to match expected coding style Changes from v18: Updated patches 2 and 3 based on input from dhildenb Added comment to patch 2 describing what keeps us from reporting a bad page Added patch to address issue with ROM devices being directly writable Changes from v19: Added std-headers change to match changes pushed for linux kernel headers Added patch to remove "report" from page hinting code paths Updated comment to better explain why we disable hints w/ page poisoning Removed code that was modifying config size for poison vs hinting Dropped x-page-poison property Added code to bounds check the reported region vs the RAM block Dropped patch for ROM devices as that was already pulled in by Paolo --- Alexander Duyck (5): linux-headers: Update to allow renaming of free_page_report_cmd_id virtio-balloon: Replace free page hinting references to 'report' with 'hint' virtio-balloon: Implement support for page poison tracking feature linux-headers: update to contain virito-balloon free page reporting virtio-balloon: Provide an interface for free page reporting hw/virtio/virtio-balloon.c | 161 ++++++++++++++++++----- include/hw/virtio/virtio-balloon.h | 23 ++- include/standard-headers/linux/virtio_balloon.h | 12 +- 3 files changed, 146 insertions(+), 50 deletions(-) --
