[dpdk-dev] [PATCH v2] net/thunderx: avoid sq door bell writes on zero packets
Kiran Kumar
kkokkilagadda at caviumnetworks.com
Wed Jul 11 10:24:36 CEST 2018
Avoid sq door bell write on zero packet case to reduce additional
traffic on register bus.
Fixes: 1c421f18e0 ("net/thunderx: add single and multi-segment Tx")
Cc: stable at dpdk.org
Signed-off-by: Kiran Kumar <kkokkilagadda at caviumnetworks.com>
---
v2 Changes:
- changed summery and description.
- added same optimization to nicvf_xmit_pkts_multiseg
drivers/net/thunderx/nicvf_rxtx.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)
diff --git a/drivers/net/thunderx/nicvf_rxtx.c b/drivers/net/thunderx/nicvf_rxtx.c
index 72305d9..6e075e2 100644
--- a/drivers/net/thunderx/nicvf_rxtx.c
+++ b/drivers/net/thunderx/nicvf_rxtx.c
@@ -162,12 +162,14 @@ nicvf_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
free_desc -= TX_DESC_PER_PKT;
}
- sq->tail = tail;
- sq->xmit_bufs += i;
- rte_wmb();
+ if (likely(i)) {
+ sq->tail = tail;
+ sq->xmit_bufs += i;
+ rte_wmb();
- /* Inform HW to xmit the packets */
- nicvf_addr_write(sq->sq_door, i * TX_DESC_PER_PKT);
+ /* Inform HW to xmit the packets */
+ nicvf_addr_write(sq->sq_door, i * TX_DESC_PER_PKT);
+ }
return i;
}
@@ -218,12 +220,14 @@ nicvf_xmit_pkts_multiseg(void *tx_queue, struct rte_mbuf **tx_pkts,
}
}
- sq->tail = tail;
- sq->xmit_bufs += used_bufs;
- rte_wmb();
+ if (likely(used_desc)) {
+ sq->tail = tail;
+ sq->xmit_bufs += used_bufs;
+ rte_wmb();
- /* Inform HW to xmit the packets */
- nicvf_addr_write(sq->sq_door, used_desc);
+ /* Inform HW to xmit the packets */
+ nicvf_addr_write(sq->sq_door, used_desc);
+ }
return i;
}
--
2.7.4
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