netdev - Re: [PATCH net 1/1] net/mlx5e: Set EQE based as default TX interrupt moderation mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20180401.205644.1807066350495572745.davem@davemloft.net>
Date:   Sun, 01 Apr 2018 20:56:44 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     saeedm@...lanox.com
Cc:     netdev@...r.kernel.org, talgi@...lanox.com
Subject: Re: [PATCH net 1/1] net/mlx5e: Set EQE based as default TX
 interrupt moderation mode

From: Saeed Mahameed <saeedm@...lanox.com>
Date: Fri, 30 Mar 2018 15:50:08 -0700

> From: Tal Gilboa <talgi@...lanox.com>
> 
> 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@...lanox.com>
> Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>

Applied and queued up for -stable.