vhost enabled vSwitch could have their own thread-safe vring enqueue policy.
Add the RTE_LIBRTE_VHOST_LOCKLESS_ENQ macro for vhost lockless enqueue.
Turn it off by default.
Signed-off-by: Huawei Xie <huawei.xie at intel.com>
---
config/common_linuxapp | 1 +
lib/librte_vhost/vhost_rxtx.c | 24 +++++++++++++++++++++++-
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/config/common_linuxapp b/config/common_linuxapp
index 0078dc9..7f59499 100644
--- a/config/common_linuxapp
+++ b/config/common_linuxapp
@@ -421,6 +421,7 @@ CONFIG_RTE_KNI_VHOST_DEBUG_TX=n
#
CONFIG_RTE_LIBRTE_VHOST=n
CONFIG_RTE_LIBRTE_VHOST_USER=y
+CONFIG_RTE_LIBRTE_VHOST_LOCKLESS_ENQ=n
CONFIG_RTE_LIBRTE_VHOST_DEBUG=n
#
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 510ffe8..475be6e 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -80,7 +80,11 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
* they need to be reserved.
*/
do {
+#ifdef RTE_LIBRTE_VHOST_LOCKESS_ENQ
res_base_idx = vq->last_used_idx_res;
+#else
+ res_base_idx = vq->last_used_idx;
+#endif
avail_idx = *((volatile uint16_t *)&vq->avail->idx);
free_entries = (avail_idx - res_base_idx);
@@ -92,10 +96,15 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
return 0;
res_end_idx = res_base_idx + count;
+
+#ifdef RTE_LIBRTE_VHOST_LOCKLESS_ENQ
/* 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);
+#else
+ /* last_used_idx_res isn't used. */
+ success = 1;
+#endif
} while (unlikely(success == 0));
res_cur_idx = res_base_idx;
LOG_DEBUG(VHOST_DATA, "(%"PRIu64") Current Index %d| End Index %d\n",
@@ -171,9 +180,11 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
rte_compiler_barrier();
+#ifdef RTE_LIBRTE_VHOST_LOCKLESS_ENQ
/* Wait until it's our turn to add our buffer to the used ring. */
while (unlikely(vq->last_used_idx != res_base_idx))
rte_pause();
+#endif
*(volatile uint16_t *)&vq->used->idx += count;
vq->last_used_idx = res_end_idx;
@@ -422,11 +433,15 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t
queue_id,
uint16_t i, id;
do {
+#ifdef RTE_LIBRTE_VHOST_LOCKLESS_ENQ
/*
* As many data cores may want access to available
* buffers, they need to be reserved.
*/
res_base_idx = vq->last_used_idx_res;
+#else
+ res_base_idx = vq->last_used_idx;
+#endif
res_cur_idx = res_base_idx;
do {
@@ -459,10 +474,15 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t
queue_id,
}
} while (pkt_len > secure_len);
+#ifdef RTE_LIBRTE_VHOST_LOCKLESS_ENQ
/* vq->last_used_idx_res is atomically updated. */
success = rte_atomic16_cmpset(&vq->last_used_idx_res,
res_base_idx,
res_cur_idx);
+#else
+ /* last_used_idx_res isn't used. */
+ success = 1;
+#endif
} while (success == 0);
id = res_base_idx;
@@ -495,12 +515,14 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t
queue_id,
rte_compiler_barrier();
+#ifdef RTE_LIBRTE_VHOST_LOCKLESS_ENQ
/*
* Wait until it's our turn to add our buffer
* to the used ring.
*/
while (unlikely(vq->last_used_idx != res_base_idx))
rte_pause();
+#endif
*(volatile uint16_t *)&vq->used->idx += entry_success;
vq->last_used_idx = res_end_idx;
--
1.8.1.4
