linux-kernel - [PATCH 5.0 029/115] net/mlx5e: Switch to Toeplitz RSS hash by default

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Message-Id: <20190424170926.744433917@linuxfoundation.org>
Date:   Wed, 24 Apr 2019 19:09:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Tariq Toukan <tariqt@...lanox.com>,
        Moshe Shemesh <moshe@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [PATCH 5.0 029/115] net/mlx5e: Switch to Toeplitz RSS hash by default

From: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>

[ Upstream commit 7ee2ace9c544a0886e02b54b625e521df8692d20 ]

Although XOR hash function can perform very well on some special use
cases, to align with all drivers, mlx5 driver should use Toeplitz hash
by default.
Toeplitz is more stable for the general use case and it is more standard
and reliable.

On top of that, since XOR (MLX5_RX_HASH_FN_INVERTED_XOR8) gives only a
repeated 8 bits pattern. When used for udp tunneling RSS source port
manipulation it results in fixed source port, which will cause bad RSS
spread.

Fixes: 2be6967cdbc9 ("net/mlx5e: Support ETH_RSS_HASH_XOR")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Reviewed-by: Tariq Toukan <tariqt@...lanox.com>
Signed-off-by: Moshe Shemesh <moshe@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -4574,7 +4574,7 @@ void mlx5e_build_rss_params(struct mlx5e
 {
 	enum mlx5e_traffic_types tt;
 
-	rss_params->hfunc = ETH_RSS_HASH_XOR;
+	rss_params->hfunc = ETH_RSS_HASH_TOP;
 	netdev_rss_key_fill(rss_params->toeplitz_hash_key,
 			    sizeof(rss_params->toeplitz_hash_key));
 	mlx5e_build_default_indir_rqt(rss_params->indirection_rqt,