[dpdk-dev] [patch v3] doc: announce API change in ethdev offload flags

Jerin Jacob Kollanukkaran jerinj at marvell.com
Thu Aug 8 12:23:16 CEST 2019


> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev at intel.com>
> Sent: Thursday, August 8, 2019 3:39 PM
> To: Jerin Jacob Kollanukkaran <jerinj at marvell.com>; Pavan Nikhilesh
> Bhagavatula <pbhagavatula at marvell.com>; stephen at networkplumber.org;
> arybchenko at solarflare.com; hemant.agrawal at nxp.com;
> thomas at monjalon.net; Yigit, Ferruh <ferruh.yigit at intel.com>; Richardson,
> Bruce <bruce.richardson at intel.com>; Neil Horman
> <nhorman at tuxdriver.com>; Mcnamara, John <john.mcnamara at intel.com>;
> Kovacevic, Marko <marko.kovacevic at intel.com>
> Cc: dev at dpdk.org
> Subject: [EXT] RE: [dpdk-dev] [patch v3] doc: announce API change in ethdev
> offload flags
> 
> External Email
> 
> ----------------------------------------------------------------------
> Hi Jerin,

Hi Konstantin,


> 
> > >
> > > Hi guys,
> > >
> > > >
> > > > From: Pavan Nikhilesh <pbhagavatula at marvell.com>
> > > >
> > > > Add new offload flags ``DEV_RX_OFFLOAD_PTYPE``,
> > > ``DEV_RX_OFFLOAD_RSS``
> > > > and ``DEV_RX_OFFLOAD_FLOW_MARK``.
> > > >
> > > > Signed-off-by: Pavan Nikhilesh <pbhagavatula at marvell.com>
> > > > Acked-by: Andrew Rybchenko <arybchenko at solarflare.com>
> > > > Acked-by: Jerin Jacob <jerinj at marvell.com>
> > > > ---
> > > >  v3 Changes:
> > > >  - DEV_RX_OFFLOAD_RSS -> DEV_RX_OFFLOAD_RSS_HASH (anndrew).
> > > >
> > > >  v2 Changes:
> > > >  - Reword for clarity.
> > > >
> > > >  doc/guides/rel_notes/deprecation.rst | 13 +++++++++++++
> > > >  1 file changed, 13 insertions(+)
> > > >
> > > > diff --git a/doc/guides/rel_notes/deprecation.rst
> > > > b/doc/guides/rel_notes/deprecation.rst
> > > > index 37b8592b6..056c5709f 100644
> > > > --- a/doc/guides/rel_notes/deprecation.rst
> > > > +++ b/doc/guides/rel_notes/deprecation.rst
> > > > @@ -78,3 +78,16 @@ Deprecation Notices
> > > >    to set new power environment if power environment was already
> > > initialized.
> > > >    In this case the function will return -1 unless the environment
> > > > is unset
> > > first
> > > >    (using ``rte_power_unset_env``). Other function usage scenarios
> > > > will not
> > > change.
> > > > +
> > > > +* ethdev: New offload flags ``DEV_RX_OFFLOAD_PTYPE``,
> > > > +``DEV_RX_OFFLOAD_RSS_HASH``
> > > > +  and ``DEV_RX_OFFLOAD_FLOW_MARK`` will be added in 19.11.
> > >
> > > One question about DEV_RX_OFFLOAD_PTYPE:
> > > Does it mean that new ol_flags value (PKT_RX_PTYPE) will be
> > > introduced to indicate that mbuf.packet_type value is set?
> > > Or PMD will have to set  mbuf.packet_type to zero, when
> > > DEV_RX_OFFLOAD_PTYPE was not enabled by user?
> >
> > I was thinking when DEV_RX_OFFLOAD_PTYPE is set
> > - mbuf.packet_type will be valid and mbuf.packet_type will have parsed
> packet type.
> > If not set
> > - mbuf.packet_type can be anything application should not use
> mbuf.packet_type field.
> 
> But in that case, we do need a new value for ol_flags, PKT_RX_PTYPE or so,
> right?

Since application has two knobs rte_eth_dev_get_supported_ptypes() and 
DEV_RX_OFFLOAD_PTYPE. We may not need to new ol_flags for this change. Right?
i.e if application sets the DEV_RX_OFFLOAD_PTYPE, The application will
get the parsed ptypes by the driver(= rte_eth_dev_get_supported_ptypes()).
So there is no scope ambiguity. Right?


> 
> >
> > This will avoid writes 0 to mbuf.packet_type and packet_type parsing if
> offload is not set.
> >
> >
> > > If so, what is the advantage?
> > > Again in that case, would it be more plausible to introduce something like:
> > > rte_eth_dev_set_supported_ptypes(uint16_t port_id, uint32_t
> > > ptype_mask); instead of DEV_RX_OFFLOAD_PTYPE?
> >
> > Any scheme is fine where we can skip the  write 0 to mbuf.packet_type
> > and packet_type parsing If application is NOT interested in packet_type.
> >
> > > Konstantin
> > >
> > > > +  This will allow application to enable or disable PMDs from
> > > > + updating ``rte_mbuf`` fields ``rte_mbuf::packet_type``,
> > > > + ``rte_mbuf::hash::rss`` and  ``rte_mbuf::hash::fdir`` respectively.
> > > > +  This scheme will allow PMDs to avoid writes to ``rte_mbuf``
> > > > + fields on Rx and  thereby improve Rx performance if application
> wishes do so.
> > > > +  In 19.11 PMDs will still update the fields even when the
> > > > + offloads are not  enabled.
> > > > +  The exact semantics of the flags will be worked out later
> > > > + either by making  them negative offloads to avoid application
> > > > + change or positive offload to  align with existing offload flag
> semantics.
> > > > --
> > > > 2.17.1



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