From ae3255bfd934be8f69ad4c960c755cddb817a12b Mon Sep 17 00:00:00 2001 From: Phil Yang Date: Thu, 3 Sep 2020 10:53:10 +0800 Subject: [PATCH] net/mlx5: relax atomic refcnt for multi-packet Rx buffer Use C11 atomics with RELAXED ordering instead of the rte_atomic ops which enforce unnecessary barriers on aarch64. Signed-off-by: Phil Yang Reviewed-by: Honnappa Nagarahalli Acked-by: Alexander Kozyrev Acked-by: Viacheslav Ovsiienko --- 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 a9ccc2be8c..c059e216d4 100644 --- a/drivers/net/mlx5/mlx5_rxq.c +++ b/drivers/net/mlx5/mlx5_rxq.c @@ -1090,7 +1090,7 @@ 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 101555ed03..0b87be15b4 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 6876c1bc4a..9ffa028d2e 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[]; /* -- 2.20.1