Re: [PATCH net-next v3] ipv6: ioam: Support for Queue depth data field

[Ido Schimmel <idosch@idosch.org>]

On Thu, Dec 30, 2021 at 06:10:04PM +0100, Justin Iurman wrote:
> v3:
>  - Report 'backlog' (bytes) instead of 'qlen' (number of packets)
> 
> v2:
>  - Fix sparse warning (use rcu_dereference)
> 
> This patch adds support for the queue depth in IOAM trace data fields.
> 
> The draft [1] says the following:
> 
>    The "queue depth" field is a 4-octet unsigned integer field.  This
>    field indicates the current length of the egress interface queue of
>    the interface from where the packet is forwarded out.  The queue
>    depth is expressed as the current amount of memory buffers used by
>    the queue (a packet could consume one or more memory buffers,
>    depending on its size).
> 
> An existing function (i.e., qdisc_qstats_qlen_backlog) is used to
> retrieve the current queue length without reinventing the wheel.
> 
> Note: it was tested and qlen is increasing when an artificial delay is
> added on the egress with tc.
> 
>   [1] https://datatracker.ietf.org/doc/html/draft-ietf-ippm-ioam-data#section-5.4.2.7
> 
> Signed-off-by: Justin Iurman <justin.iurman@uliege.be>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>