In some scenarios, mbufs returned by rte_kni_rx_burst are not freed
immediately. So kni_allocate_mbufs may be failed, but we don't know.
Even worse, when alloc_q is completely exhausted, kni_net_tx in
rte_kni.ko will drop all tx packets. kni_allocate_mbufs is never
called again, even if the mbufs are eventually freed.
In this patch, we try to allocate mbufs for alloc_q when it is empty.
According to historical experience, the performance bottleneck of KNI
is offen the usleep_range of kni thread in rte_kni.ko.
The check of kni_fifo_count is trivial and the cost should be acceptable.
Fixes: 3e12a98fe397 ("kni: optimize Rx burst")
Cc: sta...@dpdk.org
Signed-off-by: Yangchao Zhou <zhouya...@gmail.com>
---
lib/kni/rte_kni.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/kni/rte_kni.c b/lib/kni/rte_kni.c
index 8ab6c47153..bfa6a001ff 100644
--- a/lib/kni/rte_kni.c
+++ b/lib/kni/rte_kni.c
@@ -634,8 +634,8 @@ rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf
**mbufs, unsigned int num)
{
unsigned int ret = kni_fifo_get(kni->tx_q, (void **)mbufs, num);
- /* If buffers removed, allocate mbufs and then put them into alloc_q */
- if (ret)
+ /* If buffers removed or alloc_q is empty, allocate mbufs and then put
them into alloc_q */
+ if (ret || (kni_fifo_count(kni->alloc_q) == 0))
kni_allocate_mbufs(kni);
return ret;
--
2.25.1
