NAK: [PATCH] net/mlx5e: Set EQE based as default TX interrupt moderation mode

[Seth Forshee]

On Thu, Apr 12, 2018 at 01:38:19PM +0300, Talat Batheesh wrote:
> From: Tal Gilboa <talgi at mellanox.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1763325
> 
> The default TX moderation mode was mistakenly set to CQE based. The
> intention was to add a control ability in order to improve some specific
> use-cases. In general, we prefer to use EQE based moderation as it gives
> much better numbers for the common cases.
> 
> CQE based causes a degradation in the common case since it resets the
> moderation timer on CQE generation. This causes an issue when TSO is
> well utilized (large TSO sessions). The timer is set to 16us so traffic
> of ~64KB TSO sessions per second would mean timer reset (CQE per TSO
> session -> long time between CQEs). In this case we quickly reach the
> tcp_limit_output_bytes (256KB by default) and cause a halt in TX traffic.
> 
> By setting EQE based moderation we make sure timer would expire after
> 16us regardless of the packet rate.
> This fixes an up to 40% packet rate and up to 23% bandwidth degradtions.
> 
> Fixes: 0088cbbc4b66 ("net/mlx5e: Enable CQE based moderation on TX CQ")
> Signed-off-by: Tal Gilboa <talgi at mellanox.com>
> Signed-off-by: Saeed Mahameed <saeedm at mellanox.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit 48bfc39791b8b4a25f165e711f18b9c1617cefbc)
> Signed-off-by: Talat Batheesh <talatb at mellanox.com>
> 
>  Conflicts:
> 	drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> 
> Was conflict sine the mlx5e_build_nic_params changes over 4.16 kernel.

This patch has already been applied to bionic throught v4.15.17 stable
update. Thanks!