[dpdk-dev] [PATCH] kni: optimizing the rte_kni_rx_burst

[Hemant Agrawal <Hemant@freescale.com>]

The current implementation of rte_kni_rx_burst polls the fifo for buffers.
Irrespective of success or failure, it allocates the mbuf and try to put them into the alloc_q
if the buffers are not added to alloc_q, it frees them.
This waste lots of cpu cycles in allocating and freeing the buffers if alloc_q is full.

The logic has been changed to:
1. Initially allocand add buffer(burstsize) to alloc_q
2. Add buffers to alloc_q only when you are pulling out the buffers.

Signed-off-by: Hemant Agrawal <Hemant@freescale.com>
---
 lib/librte_kni/rte_kni.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
index 76feef4..01e85f8 100644
--- a/lib/librte_kni/rte_kni.c
+++ b/lib/librte_kni/rte_kni.c
@@ -263,6 +263,9 @@ rte_kni_alloc(struct rte_mempool *pktmbuf_pool,
 
 	ctx->in_use = 1;
 
+	/* Allocate mbufs and then put them into alloc_q */
+	kni_allocate_mbufs(ctx);
+
 	return ctx;
 
 fail:
@@ -369,8 +372,9 @@ rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf **mbufs, unsigned num)
 {
 	unsigned ret = kni_fifo_get(kni->tx_q, (void **)mbufs, num);
 
-	/* Allocate mbufs and then put them into alloc_q */
-	kni_allocate_mbufs(kni);
+	/* If buffers removed, allocate mbufs and then put them into alloc_q */
+	if(ret)
+		kni_allocate_mbufs(kni);
 
 	return ret;
 }
-- 
1.7.9.6