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From: "Wu, Xiaoban" <Xiaoban_Wu@student.uml.edu>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "users@dpdk.org" <users@dpdk.org>
Subject: Re: [dpdk-users] Interesting considerate but annoying behavior of MLX5 driver
Date: Fri, 27 Apr 2018 01:29:38 +0000	[thread overview]
Message-ID: <DM5PR02MB2523A48E871973443F4824F4BC8D0@DM5PR02MB2523.namprd02.prod.outlook.com> (raw)
In-Reply-To: <20180426154055.16842d96@xeon-e3>

Hi Stephen,


Thanks very much for your help. Though I don't know if it is a overkill, the following does the job.


/sbin/ethtool -s enp59s0f0 autoneg off
/sbin/ethtool -A enp59s0f0 rx off
/sbin/ethtool -A enp59s0f0 tx off


Best wishes,

Xiaoban

________________________________
From: Stephen Hemminger <stephen@networkplumber.org>
Sent: Thursday, April 26, 2018 6:40:55 PM
To: Wu, Xiaoban
Cc: users@dpdk.org
Subject: Re: [dpdk-users] Interesting considerate but annoying behavior of MLX5 driver

On Thu, 26 Apr 2018 22:26:36 +0000
"Wu, Xiaoban" <Xiaoban_Wu@student.uml.edu> wrote:

> Dear All,
>
>
> I have two Dell PowerEdge R740 servers A and B running with ubuntu 16.04, each one has a Mellanox MCX556A-ECAT NIC installed on the PCIe x16 slot. And, the two NICs are directly connected back to back with a copper cable.
>
>
> On server A, it runs a RX program which runs a function to process and analyze the received packets. On server B, it runs a packet-gen program which generates and sends packets out. They are both compiled with dpdk-17.11
>
>
> Now the interesting thing is that on server B, it is kind of smart and considerate enough to automatically adjust its TX throughput according to how fast server A processes the packets. If server A processes the packets faster, then server B sends packets with a higher throughput. Similarly, if server A processes the packets slower, then server B sends packets with a lower throughput. Please note that once the program on server B starts, it is never interrupted by any way.
>
>
> However, I think the server B should send out the packets with a constant throughput no matter how fast server A processes the packets.
>
>
> Does anybody else notice this interesting behavior of MLX5 driver? Can anybody help me disable this feature permanently? Thanks very much for your help.
>
>
> Best wishes,
>
> Xiaoban

Turn off Ethernet flow control.  It was a design mistake that NIC vendors always seem to like because it gives 0 loss benchmarks.

  reply	other threads:[~2018-04-27  1:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-26 22:26 Wu, Xiaoban
2018-04-26 22:40 ` Stephen Hemminger
2018-04-27  1:29   ` Wu, Xiaoban [this message]
2018-05-02 10:13     ` Adrien Mazarguil

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