[dpdk-dev] [PATCH v4] net/mlx5: relaxed ordering for multi-packet RQ buffer refcnt
Phil Yang
phil.yang at arm.com
Thu Sep 3 04:53:10 CEST 2020
Use c11 atomics with RELAXED ordering instead of the rte_atomic ops
which enforce unnecessary barriers on aarch64.
Signed-off-by: Phil Yang <phil.yang at arm.com>
---
v4:
Remove the unnecessary ACQUIRE barrier in rx burst path. (Honnappa)
v3:
Split from the patchset:
http://patchwork.dpdk.org/cover/68159/
drivers/net/mlx5/mlx5_rxq.c | 2 +-
drivers/net/mlx5/mlx5_rxtx.c | 16 +++++++++-------
drivers/net/mlx5/mlx5_rxtx.h | 2 +-
3 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
index 79eb8f8..40e0239 100644
--- a/drivers/net/mlx5/mlx5_rxq.c
+++ b/drivers/net/mlx5/mlx5_rxq.c
@@ -2012,7 +2012,7 @@ mlx5_mprq_buf_init(struct rte_mempool *mp, void *opaque_arg,
memset(_m, 0, sizeof(*buf));
buf->mp = mp;
- rte_atomic16_set(&buf->refcnt, 1);
+ __atomic_store_n(&buf->refcnt, 1, __ATOMIC_RELAXED);
for (j = 0; j != strd_n; ++j) {
shinfo = &buf->shinfos[j];
shinfo->free_cb = mlx5_mprq_buf_free_cb;
diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c
index 1b71e94..549477b 100644
--- a/drivers/net/mlx5/mlx5_rxtx.c
+++ b/drivers/net/mlx5/mlx5_rxtx.c
@@ -1626,10 +1626,11 @@ mlx5_mprq_buf_free_cb(void *addr __rte_unused, void *opaque)
{
struct mlx5_mprq_buf *buf = opaque;
- if (rte_atomic16_read(&buf->refcnt) == 1) {
+ if (__atomic_load_n(&buf->refcnt, __ATOMIC_RELAXED) == 1) {
rte_mempool_put(buf->mp, buf);
- } else if (rte_atomic16_add_return(&buf->refcnt, -1) == 0) {
- rte_atomic16_set(&buf->refcnt, 1);
+ } else if (unlikely(__atomic_sub_fetch(&buf->refcnt, 1,
+ __ATOMIC_RELAXED) == 0)) {
+ __atomic_store_n(&buf->refcnt, 1, __ATOMIC_RELAXED);
rte_mempool_put(buf->mp, buf);
}
}
@@ -1709,7 +1710,8 @@ mlx5_rx_burst_mprq(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
if (consumed_strd == strd_n) {
/* Replace WQE only if the buffer is still in use. */
- if (rte_atomic16_read(&buf->refcnt) > 1) {
+ if (__atomic_load_n(&buf->refcnt,
+ __ATOMIC_RELAXED) > 1) {
mprq_buf_replace(rxq, rq_ci & wq_mask, strd_n);
/* Release the old buffer. */
mlx5_mprq_buf_free(buf);
@@ -1821,9 +1823,9 @@ mlx5_rx_burst_mprq(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
void *buf_addr;
/* Increment the refcnt of the whole chunk. */
- rte_atomic16_add_return(&buf->refcnt, 1);
- MLX5_ASSERT((uint16_t)rte_atomic16_read(&buf->refcnt) <=
- strd_n + 1);
+ __atomic_add_fetch(&buf->refcnt, 1, __ATOMIC_RELAXED);
+ MLX5_ASSERT(__atomic_load_n(&buf->refcnt,
+ __ATOMIC_RELAXED) <= strd_n + 1);
buf_addr = RTE_PTR_SUB(addr, RTE_PKTMBUF_HEADROOM);
/*
* MLX5 device doesn't use iova but it is necessary in a
diff --git a/drivers/net/mlx5/mlx5_rxtx.h b/drivers/net/mlx5/mlx5_rxtx.h
index c02a007..467f31d 100644
--- a/drivers/net/mlx5/mlx5_rxtx.h
+++ b/drivers/net/mlx5/mlx5_rxtx.h
@@ -68,7 +68,7 @@ struct rxq_zip {
/* Multi-Packet RQ buffer header. */
struct mlx5_mprq_buf {
struct rte_mempool *mp;
- rte_atomic16_t refcnt; /* Atomically accessed refcnt. */
+ uint16_t refcnt; /* Atomically accessed refcnt. */
uint8_t pad[RTE_PKTMBUF_HEADROOM]; /* Headroom for the first packet. */
struct rte_mbuf_ext_shared_info shinfos[];
/*
--
2.7.4
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