On 4/7/21 11:55 AM, Balazs Nemeth wrote:
> Instead of calculating the address of a packed descriptor based on the
> vq->desc_packed and vq->last_used_idx every time, store that base
> address in desc_base. On arm, this saves 176 bytes in code size of
> function in which vhost_flush_enqueue_batch_packed gets inlined.
>
> Signed-off-by: Balazs Nemeth <bnem...@redhat.com>
> ---
> lib/librte_vhost/virtio_net.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 179c57b46..f091384a6 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -217,6 +217,8 @@ vhost_flush_enqueue_batch_packed(struct virtio_net *dev,
> {
> uint16_t i;
> uint16_t flags;
> + uint16_t last_used_idx = vq->last_used_idx;
> + struct vring_packed_desc *desc_base = &vq->desc_packed[last_used_idx];
>
> if (vq->shadow_used_idx) {
> do_data_copy_enqueue(dev, vq);
> @@ -226,16 +228,17 @@ vhost_flush_enqueue_batch_packed(struct virtio_net *dev,
> flags = PACKED_DESC_ENQUEUE_USED_FLAG(vq->used_wrap_counter);
>
> vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
> - vq->desc_packed[vq->last_used_idx + i].id = ids[i];
> - vq->desc_packed[vq->last_used_idx + i].len = lens[i];
> + desc_base[i].id = ids[i];
> + desc_base[i].len = lens[i];
> }
>
> rte_atomic_thread_fence(__ATOMIC_RELEASE);
>
> - vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE)
> - vq->desc_packed[vq->last_used_idx + i].flags = flags;
> + vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) {
> + desc_base[i].flags = flags;
> + }
>
> - vhost_log_cache_used_vring(dev, vq, vq->last_used_idx *
> + vhost_log_cache_used_vring(dev, vq, last_used_idx *
> sizeof(struct vring_packed_desc),
> sizeof(struct vring_packed_desc) *
> PACKED_BATCH_SIZE);
>
Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com>
Thanks,
Maxime
