This is a note to let you know that I've just added the patch titled
net/mlx5e: Fix small packet threshold
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-mlx5e-fix-small-packet-threshold.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sat Apr 29 08:22:13 CEST 2017
From: Eugenia Emantayev <eugenia@xxxxxxxxxxxx>
Date: Wed, 22 Mar 2017 11:44:14 +0200
Subject: net/mlx5e: Fix small packet threshold
From: Eugenia Emantayev <eugenia@xxxxxxxxxxxx>
[ Upstream commit cbad8cddb6ed7ef3a5f0a9a70f1711d4d7fb9a8f ]
RX packet headers are meant to be contained in SKB linear part,
and chose a threshold of 128.
It turns out this is not enough, i.e. for IPv6 packet over VxLAN.
In this case, UDP/IPv4 needs 42 bytes, GENEVE header is 8 bytes,
and 86 bytes for TCP/IPv6. In total 136 bytes that is more than
current 128 bytes. In this case expand header flow is reached.
The warning in skb_try_coalesce() caused by a wrong truesize
was already fixed here:
commit 158f323b9868 ("net: adjust skb->truesize in pskb_expand_head()").
Still, we prefer to totally avoid the expand header flow for performance reasons.
Tested regular TCP_STREAM with iperf for 1 and 8 streams, no degradation was found.
Fixes: 461017cb006a ("net/mlx5e: Support RX multi-packet WQE (Striding RQ)")
Signed-off-by: Eugenia Emantayev <eugenia@xxxxxxxxxxxx>
Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx5/core/en.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -82,7 +82,7 @@
#define MLX5E_VALID_NUM_MTTS(num_mtts) (MLX5_MTT_OCTW(num_mtts) <= U16_MAX)
#define MLX5_UMR_ALIGN (2048)
-#define MLX5_MPWRQ_SMALL_PACKET_THRESHOLD (128)
+#define MLX5_MPWRQ_SMALL_PACKET_THRESHOLD (256)
#define MLX5E_PARAMS_DEFAULT_LRO_WQE_SZ (64 * 1024)
#define MLX5E_DEFAULT_LRO_TIMEOUT 32
Patches currently in stable-queue which might be from eugenia@xxxxxxxxxxxx are
queue-4.9/net-mlx5e-fix-small-packet-threshold.patch