RE: [PATCH 1/6] virtio-balloon: rework deflate to add page to a list

From: Li, Liang Z
Date: Thu Jun 23 2016 - 04:30:35 EST


Hi Michael,

Could you help to review this patch set and give some comments when you have time?
My work is blocked here.

Thanks !
Liang


> -----Original Message-----
> From: Li, Liang Z
> Sent: Monday, June 13, 2016 5:47 PM
> To: kvm@xxxxxxxxxxxxxxx
> Cc: virtio-dev@xxxxxxxxxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; mst@xxxxxxxxxx; Li, Liang Z; Paolo Bonzini; Cornelia
> Huck; Amit Shah
> Subject: [PATCH 1/6] virtio-balloon: rework deflate to add page to a list
>
> will allow faster notifications using a bitmap down the road.
> Now balloon_pfn_to_page() can be removed because it is not used.
>
> Signed-off-by: Liang Li <liang.z.li@xxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
> Cc: Amit Shah <amit.shah@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_balloon.c | 22 ++++++++--------------
> 1 file changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 476c0e3..8d649a2 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -98,12 +98,6 @@ static u32 page_to_balloon_pfn(struct page *page)
> return pfn * VIRTIO_BALLOON_PAGES_PER_PAGE; }
>
> -static struct page *balloon_pfn_to_page(u32 pfn) -{
> - BUG_ON(pfn % VIRTIO_BALLOON_PAGES_PER_PAGE);
> - return pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE);
> -}
> -
> static void balloon_ack(struct virtqueue *vq) {
> struct virtio_balloon *vb = vq->vdev->priv; @@ -176,18 +170,16 @@
> static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
> return num_allocated_pages;
> }
>
> -static void release_pages_balloon(struct virtio_balloon *vb)
> +static void release_pages_balloon(struct virtio_balloon *vb,
> + struct list_head *pages)
> {
> - unsigned int i;
> - struct page *page;
> + struct page *page, *next;
>
> - /* Find pfns pointing at start of each page, get pages and free them.
> */
> - for (i = 0; i < vb->num_pfns; i +=
> VIRTIO_BALLOON_PAGES_PER_PAGE) {
> - page = balloon_pfn_to_page(virtio32_to_cpu(vb->vdev,
> - vb->pfns[i]));
> + list_for_each_entry_safe(page, next, pages, lru) {
> if (!virtio_has_feature(vb->vdev,
>
> VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
> adjust_managed_page_count(page, 1);
> + list_del(&page->lru);
> put_page(page); /* balloon reference */
> }
> }
> @@ -197,6 +189,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb,
> size_t num)
> unsigned num_freed_pages;
> struct page *page;
> struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
> + LIST_HEAD(pages);
>
> /* We can only do one array worth at a time. */
> num = min(num, ARRAY_SIZE(vb->pfns));
> @@ -208,6 +201,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb,
> size_t num)
> if (!page)
> break;
> set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
> + list_add(&page->lru, &pages);
> vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
> }
>
> @@ -219,7 +213,7 @@ static unsigned leak_balloon(struct virtio_balloon *vb,
> size_t num)
> */
> if (vb->num_pfns != 0)
> tell_host(vb, vb->deflate_vq);
> - release_pages_balloon(vb);
> + release_pages_balloon(vb, &pages);
> mutex_unlock(&vb->balloon_lock);
> return num_freed_pages;
> }
> --
> 1.9.1