From 5f22a1d87c5315a98981ecf93cd8de226cffe6ca Mon Sep 17 00:00:00 2001 From: Mark Bloch Date: Thu, 2 Nov 2017 15:22:26 +0200 Subject: [PATCH] IB/mlx4: Increase maximal message size under UD QP Maximal message should be used as a limit to the max message payload allowed, without the headers. The ConnectX-3 check is done against this value includes the headers. When the payload is 4K this will cause the NIC to drop packets. Increase maximal message to 8K as workaround, this shouldn't change current behaviour because we continue to set the MTU to 4k. To reproduce; set MTU to 4296 on the corresponding interface, for example: ifconfig eth0 mtu 4296 (both server and client) On server: ib_send_bw -c UD -d mlx4_0 -s 4096 -n 1000000 -i1 -m 4096 On client: ib_send_bw -d mlx4_0 -c UD -s 4096 -n 1000000 -i 1 -m 4096 Fixes: 6e0d733d9215 ("IB/mlx4: Allow 4K messages for UD QPs") Signed-off-by: Mark Bloch Reviewed-by: Majd Dibbiny Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford --- drivers/infiniband/hw/mlx4/qp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c index f807a6278d44..013049bcdb53 100644 --- a/drivers/infiniband/hw/mlx4/qp.c +++ b/drivers/infiniband/hw/mlx4/qp.c @@ -2215,7 +2215,7 @@ static int __mlx4_ib_modify_qp(void *src, enum mlx4_ib_source_type src_type, context->mtu_msgmax = (IB_MTU_4096 << 5) | ilog2(dev->dev->caps.max_gso_sz); else - context->mtu_msgmax = (IB_MTU_4096 << 5) | 12; + context->mtu_msgmax = (IB_MTU_4096 << 5) | 13; } else if (attr_mask & IB_QP_PATH_MTU) { if (attr->path_mtu < IB_MTU_256 || attr->path_mtu > IB_MTU_4096) { pr_err("path MTU (%u) is invalid\n", -- 2.30.2