Re: [dpdk-dev] [PATCH v2 1/5] net/mlx5: support flow count action handle

[Slava Ovsiienko <viacheslavo@nvidia.com>]

Hi, Ferruh

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Friday, April 30, 2021 11:35
> To: Slava Ovsiienko <viacheslavo@nvidia.com>; dev@dpdk.org; Andrew
> Rybchenko <andrew.rybchenko@oktetlabs.ru>
> Cc: Raslan Darawsheh <rasland@nvidia.com>; Matan Azrad
> <matan@nvidia.com>; Michael Baum <michaelba@nvidia.com>; NBU-
> Contact-Thomas Monjalon <thomas@monjalon.net>
> Subject: Re: [PATCH v2 1/5] net/mlx5: support flow count action handle
> 
> On 4/29/2021 10:55 AM, Viacheslav Ovsiienko wrote:
> > From: Michael Baum <michaelba@nvidia.com>
> >
> > Existing API supports counter action to count traffic of a single flow.
> > The user can share the count action among different flows using the
> > shared flag and the same counter ID in the count action configuration.
> >
> > Recent patch [1] introduced the indirect action API.
> > Using this API, an action can be created as indirect, unattached to
> > any flow rule.
> > Multiple flows can then be created using the same indirect action.
> > The new API also supports query operation of an indirect action.
> >
> > The new API is more efficient because the driver gets it's own handler
> > for the count action instead of managing a mapping between the user ID
> > to the driver handle.
> >
> > Support create, query and destroy indirect action operations for flow
> > count action.
> >
> > Application will use the indirect action query operation to query this
> > count action.
> >
> > In the meantime the old sharing mechanism (with the sharing flag)
> > continues to be supported, and the user can choose the way he wants to
> > share the counter.
> > The new indirect action API is only supported in DevX, so sharing
> > counter action in Verbs can only be done through the old mechanism.
> >
> 
> There is already a deprecation note to remove the 'shared' flag from counter
> action [2] in favor of 'shared actions'.
> 
> Shared action become "indirect actions" [3] which this patch implements
> 
> Is it a good time to remove the old sharing mechanism from driver since
> touching on it?

As I can see:
- it is planned to 21.11 as deprecation note says
- now there Is no support for new "indirect actions" with Verbs (not sure
 we will provide), so shared counters API might be still useful
- our CI did not migrate to the new counter approach yet (even DPDK patch is not merged yet 😊)
- hence, l would prefer keep shared counter support (by id and flag) in 21.05 
 (and very likely in 21.08), just to maintain maximal backward compatibility as long
as possible

With best regards,
Slava

> 
> 
> [2]
> https://git.dpdk.org/dpdk/tree/doc/guides/rel_notes/deprecation.rst?h=v2
> 1.05-rc1#n95
> 
> [3]
> https://git.dpdk.org/dpdk/commit/?h=v21.05-rc1&id=4b61b8774be9
> 
> 
> > [1] https://mails.dpdk.org/archives/dev/2020-July/174110.html
> >
> > Signed-off-by: Michael Baum <michaelba@nvidia.com>
> > Acked-by: Matan Azrad <matan@nvidia.com>
> 
> <...>