+static void send_balloon_page_sg(struct virtio_balloon *vb,
+ struct virtqueue *vq,
+ void *addr,
+ uint32_t size)
+{
+ unsigned int len;
+ int ret;
+
+ do {
+ ret = add_one_sg(vq, addr, size);
+ virtqueue_kick(vq);
+ wait_event(vb->acked, virtqueue_get_buf(vq, &len));
+ /*
+ * It is uncommon to see the vq is full, because the sg is sent
+ * one by one and the device is able to handle it in time. But
+ * if that happens, we go back to retry after an entry gets
+ * released.
+ */
Why send one by one though? Why not batch some s/gs and wait for all
of them to be completed? If memory if fragmented, waiting every time is
worse than what we have now (VIRTIO_BALLOON_ARRAY_PFNS_MAX at a time).