netdev - Re: [RFC net-next 2/2] ipv6: ioam: Support for Buffer occupancy data field

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Message-ID: <1780306528.220542320.1638896060436.JavaMail.zimbra@uliege.be>
Date:   Tue, 7 Dec 2021 17:54:20 +0100 (CET)
From:   Justin Iurman <justin.iurman@...ege.be>
To:     David Ahern <dsahern@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        dsahern@...nel.org, yoshfuji@...ux-ipv6.org, linux-mm@...ck.org,
        cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo kim <iamjoonsoo.kim@....com>,
        akpm@...ux-foundation.org, vbabka@...e.cz
Subject: Re: [RFC net-next 2/2] ipv6: ioam: Support for Buffer occupancy
 data field

Hi David,

>> [...]
>>
>> Signed-off-by: Justin Iurman <justin.iurman@...ege.be>
>> ---
>>  include/linux/slab.h | 15 +++++++++++++++
>>  mm/slab.h            | 14 --------------
>>  net/ipv6/ioam6.c     | 13 ++++++++++++-
>>  3 files changed, 27 insertions(+), 15 deletions(-)
>> 
> 
> this should be 2 patches - one that moves the slabinfo struct and
> function across header files and then the ioam6 change.

Agree. I didn't do it since it's "just" a RFC for now though.

> [ I agree with Jakub's line of questioning - how useful is this across
> nodes with different OS'es and s/w versions. ]

See my answer to Jakub. Also, as the draft says:

   "The units of this field
   are implementation specific.  Hence, the units are interpreted within
   the context of an IOAM-Namespace and/or node-id if used.  The authors
   acknowledge that in some operational cases there is a need for the
   units to be consistent across a packet path through the network,
   hence it is recommended for implementations to use standard units
   such as Bytes."

Therefore, what we define here is the behavior of the Linux kernel
regarding the way it handles the buffer occupancy for IOAM, and the
meaning/semantic of its value (in bytes). Having different OS'es and
s/w versions across nodes is not a problem, it's up to the operators
to bring more context to their own domains.