Messages in this thread Patch in this message | | | From | Gavin Shan <> | Subject | [PATCH v2 3/3] virtio_balloon: Specify page reporting order if needed | Date | Tue, 22 Jun 2021 15:49:26 +0800 |
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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 <david@redhat.com> Cc: virtualization@lists.linux-foundation.org Signed-off-by: Gavin Shan <gshan@redhat.com> --- 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
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