DPDK patches and discussions
 help / color / mirror / Atom feed
From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
To: dev@dpdk.org, honnappa.nagarahalli@arm.com, phil.yang@arm.com,
	jgrajcia@cisco.com, ferruh.yigit@intel.com
Cc: nd@arm.com
Subject: [dpdk-dev] [PATCH v2 8/8] net/memif: move the barrier outside the loop
Date: Mon, 28 Sep 2020 14:03:34 -0500
Message-ID: <20200928190334.40624-8-honnappa.nagarahalli@arm.com> (raw)
In-Reply-To: <20200928190334.40624-1-honnappa.nagarahalli@arm.com>

load-acquire memory order has a barrier. Loading it inside
the loop will result in a barrier in every iteration. Hence,
load the variable once outside the loop.

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
 drivers/net/memif/rte_eth_memif.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/memif/rte_eth_memif.c b/drivers/net/memif/rte_eth_memif.c
index 704350022..c73cde8fd 100644
--- a/drivers/net/memif/rte_eth_memif.c
+++ b/drivers/net/memif/rte_eth_memif.c
@@ -249,16 +249,17 @@ memif_get_buffer(struct pmd_process_private *proc_private, memif_desc_t *d)
 static void
 memif_free_stored_mbufs(struct pmd_process_private *proc_private, struct memif_queue *mq)
 {
+	uint16_t cur_tail;
 	uint16_t mask = (1 << mq->log2_ring_size) - 1;
 	memif_ring_t *ring = memif_get_ring_from_queue(proc_private, mq);
 
 	/* FIXME: improve performance */
 	/* The ring->tail acts as a guard variable between Tx and Rx
 	 * threads, so using load-acquire pairs with store-release
-	 * to synchronize it between threads.
+	 * in function eth_memif_rx for S2M queues.
 	 */
-	while (mq->last_tail != __atomic_load_n(&ring->tail,
-						__ATOMIC_ACQUIRE)) {
+	cur_tail = __atomic_load_n(&ring->tail, __ATOMIC_ACQUIRE);
+	while (mq->last_tail != cur_tail) {
 		RTE_MBUF_PREFETCH_TO_FREE(mq->buffers[(mq->last_tail + 1) & mask]);
 		/* Decrement refcnt and free mbuf. (current segment) */
 		rte_mbuf_refcnt_update(mq->buffers[mq->last_tail & mask], -1);
-- 
2.17.1


  parent reply	other threads:[~2020-09-28 19:06 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21 19:22 [dpdk-dev] [PATCH 1/4] net/memif: do not update local copy of tail in tx function Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-dev] [PATCH 2/4] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-dev] [PATCH 3/4] net/memif: relax the load of ring head pointer for S2M ring Honnappa Nagarahalli
2020-09-21 19:22 ` [dpdk-dev] [PATCH 4/4] net/memif: relax the load of ring head pointer for M2S ring Honnappa Nagarahalli
2020-09-28 19:03 ` [dpdk-dev] [PATCH v2 1/8] net/memif: do not update local copy of tail in tx function Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-dev] [PATCH v2 2/8] net/memif: relax the load of ring tail pointer for M2S ring Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-dev] [PATCH v2 3/8] net/memif: relax the load of ring head " Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-dev] [PATCH v2 4/8] net/memif: relax the load of ring head pointer for S2M ring Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-dev] [PATCH v2 5/8] net/memif: relax the load of ring head pointer for M2S zc ring Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-dev] [PATCH v2 6/8] net/memif: remove extra check Honnappa Nagarahalli
2020-09-28 19:03   ` [dpdk-dev] [PATCH v2 7/8] net/memif: relax the load of ring head pointer for S2M zc ring Honnappa Nagarahalli
2020-09-28 19:03   ` Honnappa Nagarahalli [this message]
2020-09-28 20:53   ` [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   ` Honnappa Nagarahalli
2020-10-09 11:23     ` Jakub Grajciar -X (jgrajcia - PANTHEON TECH SRO at Cisco)
2020-10-09 15:59       ` Ferruh Yigit

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200928190334.40624-8-honnappa.nagarahalli@arm.com \
    --to=honnappa.nagarahalli@arm.com \
    --cc=dev@dpdk.org \
    --cc=ferruh.yigit@intel.com \
    --cc=jgrajcia@cisco.com \
    --cc=nd@arm.com \
    --cc=phil.yang@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror https://inbox.dpdk.org/dev/0 dev/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 dev dev/ https://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


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