netdev - Re: [PATCH] net: make tc-police action MTU behavior match documentation

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Date:   Wed, 28 Feb 2018 16:14:08 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Andrew Collins <acollins@...dlepoint.com>
Cc:     Jamal Hadi Salim <jhs@...atatu.com>,
        David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: make tc-police action MTU behavior match documentation

On Tue, Feb 27, 2018 at 9:41 AM, Andrew Collins
<acollins@...dlepoint.com> wrote:
>> I don't find such statement from the man page:
>> http://man7.org/linux/man-pages/man8/tc-police.8.html
>
>
>> What am I missing?
>
> Under MTU the man page states:
>
> mtu BYTES[/BYTES]
>               This is the maximum packet size handled by the policer (larger ones will be handled like they exceeded the configured rate). Setting this value correctly will improve the scheduler's precision.
>               Value  formatting  is identical to burst above. ->Defaults to unlimited<-.
>
> Peakrate requiring MTU isn't mentioned directly in the man page, but if you provide peakrate without MTU, tc complains:
>
> "mtu" is required, if "peakrate" is requested.
>
> The idea here is just to make the actual implementation match these two statements, MTU is unlimited, unless you use peakrate in which case you have to provide it (although if you craft netlink messages without tc you can set peakrate with no mtu, and the action will still default to a reasonable mtu rather than falling over).
>

If this is just an iproute2 issue, please fix it there rather in kernel.