[dpdk-dev] [PATCH v2] doc: update mlx5 flow count limitations

[Ori Kam]

> -----Original Message-----
> From: Nélio Laranjeiro [mailto:nelio.laranjeiro at 6wind.com]
> Sent: Monday, October 16, 2017 3:36 PM
> To: Ori Kam <orika at mellanox.com>
> Cc: Adrien Mazarguil <adrien.mazarguil at 6wind.com>; Yongseok Koh
> <yskoh at mellanox.com>; dev at dpdk.org
> Subject: Re: [PATCH v2] doc: update mlx5 flow count limitations
> 
> On Mon, Oct 16, 2017 at 11:31:32AM +0000, Ori Kam wrote:
> > Please see my comments,
> >
> > > -----Original Message-----
> > > From: Nélio Laranjeiro [mailto:nelio.laranjeiro at 6wind.com]
> > > Sent: Monday, October 16, 2017 2:18 PM
> > > To: Ori Kam <orika at mellanox.com>
> > > Cc: Adrien Mazarguil <adrien.mazarguil at 6wind.com>; Yongseok Koh
> > > <yskoh at mellanox.com>; dev at dpdk.org
> > > Subject: Re: [PATCH v2] doc: update mlx5 flow count limitations
> > >
> > > On Mon, Oct 16, 2017 at 11:32:39AM +0300, Ori Kam wrote:
> > > > Signed-off-by: Ori Kam <orika at mellanox.com>
> > > > Acked-by: Shahaf Shuler <shahafs at mellanox.com>
> > > > ---
> > > >  doc/guides/nics/mlx5.rst |    5 ++++-
> > > >  1 files changed, 4 insertions(+), 1 deletions(-)
> > > >
> > > > diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
> > > > index
> > > > d24941a..7da5c87 100644
> > > > --- a/doc/guides/nics/mlx5.rst
> > > > +++ b/doc/guides/nics/mlx5.rst
> > > > @@ -104,7 +104,8 @@ Limitations
> > > >  -----------
> > > >
> > > >  - Inner RSS for VXLAN frames is not supported yet.
> > > > -- Port statistics through software counters only.
> > > > +- Port statistics through software counters only. Flow statistics
> > > > +are
> > > > +  supported by hardware counters.
> > > >  - Hardware checksum RX offloads for VXLAN inner header are not
> > > supported yet.
> > > >  - Forked secondary process not supported.
> > > >  - Flow pattern without any specific vlan will match for vlan packets as
> well:
> > > > @@ -127,6 +128,8 @@ Limitations
> > > >  - A multi segment packet must have less than 6 segments in case
> > > > the Tx
> > > burst function
> > > >    is set to multi-packet send or Enhanced multi-packet send.
> > > > Otherwise it
> > > must have
> > > >    less than 50 segments.
> > > > +- Count action for RTE flow is only supported in OFED 4.2.
> > > > +- Two identical rules with count action are not supported.
> > >
> > > This last line does not bring anything, having two identical rules
> > > already create a collision which is not defined by the flow API.
> > > In PMD situation is is even worse, as it will match both rules and
> > > thus it will duplicate a packet.
> > >
> > > There is no need to add a limit on an undefined behavior by the API itself.
> > >
> >
> > The thing is that when you try adding duplicate rules without the
> > count it works without any error while if you add the count action then for
> the second rule you get an error.
> > This line address this inconsistency.
> 
> According to Flow API documentation [1]
> 
> "If a packet is matched by several rules of a given group for a given priority
> level, the outcome is undefined. It can take any path, may be duplicated or
> even cause unrecoverable errors."
> 
> This is already documented and application makers should avoid it.
> There is no need to duplicate this information.
> 

Will fix in version 3.

> > > Thanks,
> > >
> > > PS: when you send a new revision, please use the --thread and
> > > --in-reply-to to link it with the previous one.
> > >
> >
> >
> > My bad,
> >
> > > --
> > > Nélio Laranjeiro
> > > 6WIND
> >
> > Regards,
> > Ori Kam
> 
> Thanks,
> 
> [1]
> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdpd
> k.org%2Fdoc%2Fguides%2Fprog_guide%2Frte_flow.html&data=02%7C01%7
> Corika%40mellanox.com%7Ccc884d2a17c641d6388b08d51492886c%7Ca65297
> 1c7d2e4d9ba6a4d149256f461b%7C0%7C0%7C636437541948539609&sdata=fh
> 67Sys0ZaabU6hmpv5uo%2BgfXlRe2eDjTn65MUVO7IU%3D&reserved=0
> 
> --
> Nélio Laranjeiro
> 6WIND

Regards,
Ori Kam