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From: =?UTF-8?Q?Jan_M=C4=99dala?= <jan@semihalf.com>
Date: Thu, 7 Jul 2016 13:33:48 +0200
Message-ID: <CANw_3ZezssBwyV8DOrJSN7-ygm0GKEz1PnD41RMkM=suN7FBag@mail.gmail.com>
To: dev@dpdk.org
Cc: Alexander Matushevsky <alex@annapurnalabs.com>,
=?UTF-8?Q?Jan_M=C4=99dala?= <jan@semihalf.com>
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Subject: [dpdk-dev] [PATCH] ena: fix doorbell submission when not needed
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Avoid submitting doorbell when:
* no packets have been submitted to TX
* no free resources have been submitted while RX
Sending doorbell without actual work to be performed by device
violates ENA specification and can lead to unpredictable behavior.
Fixes: 1173fca25af9 ("ena: add polling-mode driver")
Signed-off-by: Alexander Matushevsky <matua@amazon.com>
Signed-off-by: Jan Medala <jan@semihalf.com>
---
drivers/net/ena/ena_ethdev.c | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)
diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index 702289b..d68e7ec 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -920,10 +920,14 @@ static int ena_populate_rx_queue(struct ena_ring
*rxq, unsigned int count)
next_to_use = ENA_RX_RING_IDX_NEXT(next_to_use, ring_size);
}
- rte_wmb();
- rxq->next_to_use = next_to_use;
- /* let HW know that it can fill buffers with data */
- ena_com_write_sq_doorbell(rxq->ena_com_io_sq);
+ /* When we submitted free recources to device... */
+ if (i > 0) {
+ /* ...let HW know that it can fill buffers with data */
+ rte_wmb();
+ ena_com_write_sq_doorbell(rxq->ena_com_io_sq);
+
+ rxq->next_to_use = next_to_use;
+ }
return i;
}
@@ -1316,7 +1320,7 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue,
struct rte_mbuf **tx_pkts,
struct ena_tx_buffer *tx_info;
struct ena_com_buf *ebuf;
uint16_t rc, req_id, total_tx_descs = 0;
- int sent_idx = 0;
+ uint16_t sent_idx = 0;
int nb_hw_desc;
/* Check adapter state */
@@ -1395,9 +1399,14 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue,
struct rte_mbuf **tx_pkts,
next_to_use = ENA_TX_RING_IDX_NEXT(next_to_use, ring_size);
}
- /* Let HW do it's best :-) */
- rte_wmb();
- ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
+ /* If there are ready packets to be xmitted... */
+ if (sent_idx > 0) {
+ /* ...let HW do its best :-) */
+ rte_wmb();
+ ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
+
+ tx_ring->next_to_use = next_to_use;
+ }
/* Clear complete packets */
while (ena_com_tx_comp_req_id_get(tx_ring->ena_com_io_cq, &req_id) >= 0) {
@@ -1420,9 +1429,11 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue,
struct rte_mbuf **tx_pkts,
break;
}
- /* acknowledge completion of sent packets */
- ena_com_comp_ack(tx_ring->ena_com_io_sq, total_tx_descs);
- tx_ring->next_to_use = next_to_use;
+ if (total_tx_descs > 0) {
+ /* acknowledge completion of sent packets */
+ ena_com_comp_ack(tx_ring->ena_com_io_sq, total_tx_descs);
+ }
+
return sent_idx;
}
--
2.8.1