vhost: comment identified issues

1) FIXME: concurrent calls to vhost set mem table from different guests
could cause mem_temp to be overrided.
2) TODO: cmpset cost quite some cpu cyles. Allow app to disable this
feature if there is no contention in real workload.
3) FIXME: fix scatter gather mbuf copy to vhost vring chained buffers.

Signed-off-by: Huawei Xie <huawei.xie@intel.com>
Acked-by: Changchun Ouyang <changchun.ouyang@intel.com>

diff --git a/lib/librte_vhost/vhost-net-cdev.c b/lib/librte_vhost/vhost-net-cdev.c
index e5875eb..91ff0d8 100644 (file)
--- a/lib/librte_vhost/vhost-net-cdev.c
+++ b/lib/librte_vhost/vhost-net-cdev.c
@@ -214,6 +214,7 @@ vhost_net_ioctl(fuse_req_t req, int cmd, void *arg,
                break;
 
        case VHOST_SET_MEM_TABLE:
+               /*TODO fix race condition.*/
                LOG_DEBUG(VHOST_CONFIG, "(%"PRIu64") IOCTL: VHOST_SET_MEM_TABLE\n", ctx.fh);
                static struct vhost_memory mem_temp;
 

diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 2a1171a..84ec0e8 100644 (file)
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -93,6 +93,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
 
                res_end_idx = res_base_idx + count;
                /* vq->last_used_idx_res is atomically updated. */
+               /* TODO: Allow to disable cmpset if no concurrency in application. */
                success = rte_atomic16_cmpset(&vq->last_used_idx_res,
                                res_base_idx, res_end_idx);
        } while (unlikely(success == 0));
@@ -146,6 +147,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
                vq->used->ring[res_cur_idx & (vq->size - 1)].len = packet_len;
 
                /* Copy mbuf data to buffer */
+               /* FIXME for sg mbuf and the case that desc couldn't hold the mbuf data */
                rte_memcpy((void *)(uintptr_t)buff_addr,
                        rte_pktmbuf_mtod(buff, const void *),
                        rte_pktmbuf_data_len(buff));