On Tue, Apr 26, 2016 at 04:05:24PM +0800, Zhou Jie wrote:
> virtio_net_flush_tx has a huge stack usage of 16392 bytes approx.
> Moving large arrays to heap to reduce stack usage.
>
> Signed-off-by: Zhou Jie <zhoujie2...@cn.fujitsu.com>
I don't think it's appropriate for trivial.
Also - what's the point, exactly?
> ---
> hw/net/virtio-net.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 5798f87..cab7bbc 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1213,6 +1213,7 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
> VirtIONet *n = q->n;
> VirtIODevice *vdev = VIRTIO_DEVICE(n);
> VirtQueueElement *elem;
> + struct iovec *sg = NULL, *sg2 = NULL;
> int32_t num_packets = 0;
> int queue_index = vq2q(virtio_get_queue_index(q->tx_vq));
> if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> @@ -1224,10 +1225,12 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
> return num_packets;
> }
>
> + sg = g_new(struct iovec, VIRTQUEUE_MAX_SIZE);
> + sg2 = g_new(struct iovec, VIRTQUEUE_MAX_SIZE + 1);
> for (;;) {
> ssize_t ret;
> unsigned int out_num;
> - struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE + 1],
> *out_sg;
> + struct iovec *out_sg;
> struct virtio_net_hdr_mrg_rxbuf mhdr;
>
> elem = virtqueue_pop(q->tx_vq, sizeof(VirtQueueElement));
> @@ -1252,7 +1255,7 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
> virtio_net_hdr_swap(vdev, (void *) &mhdr);
> sg2[0].iov_base = &mhdr;
> sg2[0].iov_len = n->guest_hdr_len;
> - out_num = iov_copy(&sg2[1], ARRAY_SIZE(sg2) - 1,
> + out_num = iov_copy(&sg2[1], VIRTQUEUE_MAX_SIZE,
> out_sg, out_num,
> n->guest_hdr_len, -1);
> if (out_num == VIRTQUEUE_MAX_SIZE) {
> @@ -1269,10 +1272,10 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
> */
> assert(n->host_hdr_len <= n->guest_hdr_len);
> if (n->host_hdr_len != n->guest_hdr_len) {
> - unsigned sg_num = iov_copy(sg, ARRAY_SIZE(sg),
> + unsigned sg_num = iov_copy(sg, VIRTQUEUE_MAX_SIZE,
> out_sg, out_num,
> 0, n->host_hdr_len);
> - sg_num += iov_copy(sg + sg_num, ARRAY_SIZE(sg) - sg_num,
> + sg_num += iov_copy(sg + sg_num, VIRTQUEUE_MAX_SIZE - sg_num,
> out_sg, out_num,
> n->guest_hdr_len, -1);
> out_num = sg_num;
> @@ -1284,6 +1287,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
> if (ret == 0) {
> virtio_queue_set_notification(q->tx_vq, 0);
> q->async_tx.elem = elem;
> + g_free(sg);
> + g_free(sg2);
> return -EBUSY;
> }
>
> @@ -1296,6 +1301,8 @@ drop:
> break;
> }
> }
> + g_free(sg);
> + g_free(sg2);
> return num_packets;
> }
>
> --
> 2.5.5
>
>
