[PATCH v2 3/3] virtio_balloon: Specify page reporting order if needed
From: Gavin Shan <hidden>
Date: 2021-06-22 05:49:11
Also in:
lkml
Subsystem:
the rest, virtio balloon, virtio core · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", David Hildenbrand, Jason Wang
The page reporting won't be triggered if the freeing page can't come
up with a free area, whose size is equal or bigger than the threshold
(page reporting order). The default page reporting order, equal to
@pageblock_order, is too huge on some architectures to trigger page
reporting. One example is ARM64 when 64KB base page size is used.
PAGE_SIZE: 64KB
pageblock_order: 13 (512MB)
MAX_ORDER: 14
This specifies the page reporting order to 5 (2MB) for this specific
case so that page reporting can be triggered.
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: David Hildenbrand <redacted>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: Gavin Shan <redacted>
---
drivers/virtio/virtio_balloon.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 510e9318854d..fd419780cc23 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c@@ -993,6 +993,23 @@ static int virtballoon_probe(struct virtio_device *vdev) goto out_unregister_oom; } + /* + * The default page reporting order is @pageblock_order, which + * corresponds to 512MB in size on ARM64 when 64KB base page + * size is used. The page reporting won't be triggered if the + * freeing page can't come up with a free area like that huge. + * So we specify the page reporting order to 5, corresponding + * to 2MB. It helps to avoid THP splitting if 4KB base page + * size is used by host. + * + * Ideallh, the page reporting order is selected based on the + * host's base page size. However, it needs more work to report + * that value. The hardcoded order would be fine currently. + */ +#if defined(CONFIG_ARM64) && defined(CONFIG_ARM64_64K_PAGES) + vb->pr_dev_info.order = 5; +#endif + err = page_reporting_register(&vb->pr_dev_info); if (err) goto out_unregister_oom;
--
2.23.0