patch 'common/mlx5: fix queue pair ack timeout configuration' has been queued to stable release 21.11.1

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 21.11.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 03/06/22. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable/commit/b8bc6f4256a25a01c7ac787b68823c6e95a9e7b9

Thanks.

Kevin

---
>From b8bc6f4256a25a01c7ac787b68823c6e95a9e7b9 Mon Sep 17 00:00:00 2001
From: Yajun Wu <yajunw at nvidia.com>
Date: Mon, 14 Feb 2022 08:03:19 +0200
Subject: [PATCH] common/mlx5: fix queue pair ack timeout configuration
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

[ upstream commit 05b54bf0892dcd1e3698ba86a297722b7566cc10 ]

VDPA driver creates two QPs(1 queue pair include 1 send queue
and 1 receive queue) per virtio queue to get traffic events
from NIC to SW.
Two QPs(called FW QP and SW QP) are created as loopback QP
and FW QP'SQ is connected to SW QP'RQ internally.

When packet receive or send out, HW will send WQE by FW QP'SQ,
then SW will get CQE from the CQ of SW QP.

With large scale and heavy traffic, the SQ's request may fail
to get ACK from RQ HW, because HW is busy.
SQ will retry the request with qpc.retry_count times and each time
wait for 4.096 uS *2^(ack_timeout) for the response. If still can’t
get RQ’s HW response, SQ will go to an error state.

16 is experienced value. It should not be too high or too low.
Too high will make QP waits too long in case it’s packet drop.
Too low will cause QP to go to an error state(retry-exceeded) easily.

Fixes: 15c3807e86ab ("common/mlx5: support DevX QP operations")

Signed-off-by: Yajun Wu <yajunw at nvidia.com>
Acked-by: Matan Azrad <matan at nvidia.com>
---
 drivers/common/mlx5/mlx5_devx_cmds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/common/mlx5/mlx5_devx_cmds.c b/drivers/common/mlx5/mlx5_devx_cmds.c
index 2e807a0829..7732613c69 100644
--- a/drivers/common/mlx5/mlx5_devx_cmds.c
+++ b/drivers/common/mlx5/mlx5_devx_cmds.c
@@ -2280,5 +2280,5 @@ mlx5_devx_cmd_modify_qp_state(struct mlx5_devx_obj *qp, uint32_t qp_st_mod_op,
 		qpc = MLX5_ADDR_OF(rtr2rts_qp_in, &in, qpc);
 		MLX5_SET(rtr2rts_qp_in, &in, qpn, qp->id);
-		MLX5_SET(qpc, qpc, primary_address_path.ack_timeout, 14);
+		MLX5_SET(qpc, qpc, primary_address_path.ack_timeout, 16);
 		MLX5_SET(qpc, qpc, log_ack_req_freq, 0);
 		MLX5_SET(qpc, qpc, retry_count, 7);
-- 
2.34.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2022-03-01 10:41:03.588435064 +0000
+++ 0079-common-mlx5-fix-queue-pair-ack-timeout-configuration.patch	2022-03-01 10:41:01.401244118 +0000
@@ -1 +1 @@
-From 05b54bf0892dcd1e3698ba86a297722b7566cc10 Mon Sep 17 00:00:00 2001
+From b8bc6f4256a25a01c7ac787b68823c6e95a9e7b9 Mon Sep 17 00:00:00 2001
@@ -8,0 +9,2 @@
+[ upstream commit 05b54bf0892dcd1e3698ba86a297722b7566cc10 ]
+
@@ -29 +30,0 @@
-Cc: stable at dpdk.org