From 9f9bebae55309c1230d2b9a81ece2f94f1eeda69 Mon Sep 17 00:00:00 2001 From: Shahaf Shuler Date: Sun, 27 Aug 2017 09:47:09 +0300 Subject: [PATCH] net/mlx5: don't map doorbell register to write combining By default, Verbs maps the doorbell register to write combining. Working with write combining is useful for drivers which use blue flame for the doorbell write. Since mlx5 PMD uses only doorbells and write combining mapping requires an extra memory barrier to flush the doorbell after its write, setting the mapping to un-cached by default. Such change is expected to reduce the max and average round trip latency. Signed-off-by: Shahaf Shuler Signed-off-by: Yongseok Koh Signed-off-by: Alexander Solganik Signed-off-by: Sagi Grimberg Acked-by: Nelio Laranjeiro --- drivers/net/mlx5/mlx5.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c index bd66a7c77a..50f4ba70a3 100644 --- a/drivers/net/mlx5/mlx5.c +++ b/drivers/net/mlx5/mlx5.c @@ -884,6 +884,8 @@ rte_mlx5_pmd_init(void) * using this PMD, which is not supported in forked processes. */ setenv("RDMAV_HUGEPAGES_SAFE", "1", 1); + /* Don't map UAR to WC if BlueFlame is not used.*/ + setenv("MLX5_SHUT_UP_BF", "1", 1); ibv_fork_init(); rte_pci_register(&mlx5_driver); } -- 2.20.1