On SMT systems when a spinloop is done without a pause it may cause excessive latency. This problem was found by the fix_empty_spinloops coccinelle script.
This is compile tested only! I don't have this hardware. Signed-off-by: Stephen Hemminger <[email protected]> --- drivers/net/cnxk/cn10k_tx.h | 4 ++-- drivers/net/cnxk/cn20k_tx.h | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/cnxk/cn10k_tx.h b/drivers/net/cnxk/cn10k_tx.h index be9e020ac5..3f4cad168c 100644 --- a/drivers/net/cnxk/cn10k_tx.h +++ b/drivers/net/cnxk/cn10k_tx.h @@ -167,7 +167,7 @@ cn10k_nix_vwqe_wait_fc(struct cn10k_eth_txq *txq, uint16_t req) #else RTE_SET_USED(pkts); while (rte_atomic_load_explicit(&txq->fc_cache_pkts, rte_memory_order_relaxed) < 0) - ; + rte_pause(); #endif cached = rte_atomic_fetch_sub_explicit(&txq->fc_cache_pkts, req, rte_memory_order_acquire) - req; @@ -402,7 +402,7 @@ cn10k_nix_sec_fc_wait(struct cn10k_eth_txq *txq, uint16_t nb_pkts) #else /* Wait for primary core to refill FC. */ while (rte_atomic_load_explicit(fc_sw, rte_memory_order_relaxed) < 0) - ; + rte_pause(); #endif val = rte_atomic_fetch_sub_explicit(fc_sw, nb_pkts, rte_memory_order_acquire) - nb_pkts; diff --git a/drivers/net/cnxk/cn20k_tx.h b/drivers/net/cnxk/cn20k_tx.h index 9e48744831..3dfad5fd5a 100644 --- a/drivers/net/cnxk/cn20k_tx.h +++ b/drivers/net/cnxk/cn20k_tx.h @@ -165,7 +165,7 @@ cn20k_nix_vwqe_wait_fc(struct cn20k_eth_txq *txq, uint16_t req) #else RTE_SET_USED(pkts); while (rte_atomic_load_explicit(&txq->fc_cache_pkts, rte_memory_order_relaxed) < 0) - ; + rte_pause(); #endif cached = rte_atomic_fetch_sub_explicit(&txq->fc_cache_pkts, req, rte_memory_order_acquire) - req; @@ -392,7 +392,7 @@ cn20k_nix_sec_fc_wait(struct cn20k_eth_txq *txq, uint16_t nb_pkts) #else /* Wait for primary core to refill FC. */ while (rte_atomic_load_explicit(fc_sw, rte_memory_order_relaxed) < 0) - ; + rte_pause(); #endif val = rte_atomic_fetch_sub_explicit(fc_sw, nb_pkts, rte_memory_order_acquire) - nb_pkts; -- 2.51.0
