patches for DPDK stable branches
 help / color / Atom feed
* [dpdk-stable] [PATCH 1/4] net/memif: do not update local copy of tail in tx function
@ 2020-09-21 19:22 Honnappa Nagarahalli
  2020-09-21 19:22 ` [dpdk-stable] [PATCH 2/4] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
                   ` (3 more replies)
  0 siblings, 4 replies; 13+ messages in thread
From: Honnappa Nagarahalli @ 2020-09-21 19:22 UTC (permalink / raw)
  To: dev, honnappa.nagarahalli, phil.yang, jgrajcia, ferruh.yigit; +Cc: nd, stable

In the case of S2M queues, the receiver synchronizes with the sender
(i.e. informs of the packets it has received) using ring->tail.
Hence, the sender does not need to update last_tail.

In the case of M2S queues, the receiver uses last_tail to
keep track of the descriptors it has received. The
sender is not required to update the last_tail. Updating
the last_tail makes it a shared variable between the
transmitter and receiver affecting the performance.

Fixes: 09c7e63a71f9 ("net/memif: introduce memory interface PMD")
Cc: jgrajcia@cisco.com
Cc: stable@dpdk.org

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
---
 drivers/net/memif/rte_eth_memif.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c
index c1c7e9f8d..fd7dbc53e 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -568,12 +568,10 @@ eth_memif_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 	ring_size = 1 << mq->log2_ring_size;
 	mask = ring_size - 1;
 
-	n_free = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE) - mq->last_tail;
-	mq->last_tail += n_free;
-
 	if (type == MEMIF_RING_S2M) {
 		slot = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE);
-		n_free = ring_size - slot + mq->last_tail;
+		n_free = ring_size - slot +
+				__atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
 	} else {
 		slot = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
 		n_free = __atomic_load_n(&ring->head, __ATOMIC_ACQUIRE) - slot;
-- 
2.17.1


^ permalink raw reply	[flat|nested] 13+ messages in thread

end of thread, back to index

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-09-21 19:22 [dpdk-stable] [PATCH 1/4] net/memif: do not update local copy of tail in tx function Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-stable] [PATCH 2/4] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-stable] [PATCH 3/4] net/memif: relax the load of ring head pointer for S2M ring Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-stable] [PATCH 4/4] net/memif: relax the load of ring head pointer for M2S ring Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-stable] [PATCH v2 1/8] net/memif: do not update local copy of tail in tx function Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-stable] [PATCH v2 2/8] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-stable] [PATCH v2 3/8] net/memif: relax the load of ring head " Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-stable] [PATCH v2 4/8] net/memif: relax the load of ring head pointer for S2M ring Honnappa Nagarahalli
2020-09-28 20:53   ` [dpdk-stable] [dpdk-dev] [PATCH v2 1/8] net/memif: do not update local copy of tail in tx function Stephen Hemminger
2020-09-29  5:24     ` Honnappa Nagarahalli
2020-10-07 17:08   ` [dpdk-stable] " Honnappa Nagarahalli
2020-10-09 11:23     ` Jakub Grajciar -X (jgrajcia - PANTHEON TECH SRO at Cisco)
2020-10-09 15:59       ` Ferruh Yigit

patches for DPDK stable branches

Archives are clonable:
	git clone --mirror http://inbox.dpdk.org/stable/0 stable/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 stable stable/ http://inbox.dpdk.org/stable \
		stable@dpdk.org
	public-inbox-index stable


Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.stable


AGPL code for this site: git clone https://public-inbox.org/ public-inbox