Re: [dpdk-dev] [PATCH] net/mlx5: fix Tx queue size created with DevX

Hi,

-----Original Message-----
From: Viacheslav Ovsiienko <redacted>
Sent: Thursday, February 4, 2021 2:04 PM
To: dev@dpdk.org
Cc: Raslan Darawsheh <redacted>; Matan Azrad
[off-list ref]; Ori Kam [off-list ref]; NBU-Contact-Thomas
Monjalon [off-list ref]; stable@dpdk.org
Subject: [PATCH] net/mlx5: fix Tx queue size created with DevX

The number of descriptors specified for queue creation
implies the queue should be able to contain the specified
amount of packets being sent. Typically one packet takes
one queue descriptor (WQE) to be handled. If there is inline
data option enabled one packet might require more WQEs to
embrace the inline data and the overall queue size (the
number of queue descriptors) should be adjusted accordingly.

In mlx5 PMD the queues can be created either via Verbs, using
the rdma-core library or via DevX as direct kernel/firmware call.
The rdma-core does queue size adjustment internally, depending on
TSO and inline setting. The DevX approach missed this point.
This caused the queue size discrepancy and performance variations.

The patch adjusts the Tx queue size for the DexV approach
in the same as it is done in rdma-core implementation.

Fixes: 86d259cec852 ("net/mlx5: separate Tx queue object creations")
Cc: stable@dpdk.org

Signed-off-by: Viacheslav Ovsiienko <redacted>

Patch applied to next-net-mlx,

Kindest regards,
Raslan Darawsheh