netdev - Re: [PATCH net-next 0/6] mlxsw: Add support of latency TLV

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Date:   Thu, 19 Jan 2023 17:18:04 -0800
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     Petr Machata <petrm@...dia.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "Paolo Abeni" <pabeni@...hat.com>, <netdev@...r.kernel.org>
CC:     Ido Schimmel <idosch@...dia.com>, Amit Cohen <amcohen@...dia.com>,
        Danielle Ratson <danieller@...dia.com>, <mlxsw@...dia.com>
Subject: Re: [PATCH net-next 0/6] mlxsw: Add support of latency TLV



On 1/19/2023 2:32 AM, Petr Machata wrote:
> Amit Cohen writes:
> 
> Ethernet Management Datagrams (EMADs) are Ethernet packets sent between
> the driver and device's firmware. They are used to pass various
> configurations to the device, but also to get events (e.g., port up)
> from it. After the Ethernet header, these packets are built in a TLV
> format.
> 
> This is the structure of EMADs:
> * Ethernet header
> * Operation TLV
> * String TLV (optional)
> * Latency TLV (optional)
> * Reg TLV
> * End TLV
> 
> The latency of each EMAD is measured by firmware. The driver can get the
> measurement via latency TLV which can be added to each EMAD. This TLV is
> optional, when EMAD is sent with this TLV, the EMAD's response will include
> the TLV and will contain the firmware measurement.
> 
> Add support for Latency TLV and use it by default for all EMADs (see
> more information in commit messages). The latency measurements can be
> processed using BPF program for example, to create a histogram and average
> of the latency per register. In addition, it is possible to measure the
> end-to-end latency, so then the latency of the software overhead can be
> calculated. This information can be useful to improve the driver
> performance.

...

> Patch set overview:
> Patches #1-#3 add support for querying MGIR, to know if string TLV and
> latency TLV are supported
> Patches #4-#5 add some relevant fields to support latency TLV
> Patch #6 adds support of latency TLV
> 
> Amit Cohen (6):
>    mlxsw: reg: Add TLV related fields to MGIR register
>    mlxsw: Enable string TLV usage according to MGIR output
>    mlxsw: core: Do not worry about changing 'enable_string_tlv' while
>      sending EMADs
>    mlxsw: emad: Add support for latency TLV
>    mlxsw: core: Define latency TLV fields
>    mlxsw: Add support of latency TLV

Looks ok to me.

Reviewed-by: Tony Nguyen <anthony.l.nguyen@...el.com>

>   drivers/net/ethernet/mellanox/mlxsw/core.c    | 108 ++++++++++++++----
>   drivers/net/ethernet/mellanox/mlxsw/core.h    |   2 -
>   drivers/net/ethernet/mellanox/mlxsw/emad.h    |   4 +
>   drivers/net/ethernet/mellanox/mlxsw/reg.h     |  12 ++
>   .../net/ethernet/mellanox/mlxsw/spectrum.c    |   1 -
>   5 files changed, 103 insertions(+), 24 deletions(-)
>