Re: [dpdk-dev] [PATCH v2] app/testpmd: support age shared action context

[Matan Azrad <matan@nvidia.com>]

From: Ferruh Yigit
> On 11/7/2020 5:30 PM, Matan Azrad wrote:
> > Hi Ferruh
> >
> > From: Ferruh Yigit
> >> On 11/5/2020 9:32 PM, Matan Azrad wrote:
> >>> When an age action becomes aged-out the rte_flow_get_aged_flows
> >>> should return the action context supplied by the configuration structure.
> >>>
> >>> In case the age action created by the shared action API, the shared
> >>> action context of the Testpmd application was not set.
> >>>
> >>> In addition, the application handler of the contexts returned by the
> >>> rte_flow_get_aged_flows API didn't consider the fact that the action
> >>> could be set by the shared action API and considered it as regular
> >>> flow context.
> >>>
> >>> This caused a crash in Testpmd when the context is parsed.
> >>>
> >>> This patch set context type in the flow and shared action context
> >>> and uses it to parse the aged-out contexts correctly.
> >>>
> >>> Signed-off-by: Matan Azrad <matan@nvidia.com>
> >>> Acked-by: Dekel Peled <dekelp@nvidia.com>
> >>> ---
> >>>    app/test-pmd/config.c  | 119
> >>> ++++++++++++++++++++++++++++++++++-------
> >> --------
> >>>    app/test-pmd/testpmd.h |   5 +++
> >>>    2 files changed, 87 insertions(+), 37 deletions(-)
> >>>
> >>> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c index
> >>> 755d1df..00a7dd1 100644
> >>> --- a/app/test-pmd/config.c
> >>> +++ b/app/test-pmd/config.c
> >>> @@ -1763,6 +1763,33 @@ void port_flow_tunnel_create(portid_t
> >>> port_id,
> >> const struct tunnel_ops *ops)
> >>>        }
> >>>    }
> >>>
> >>> +#define AGE_ACTION_TYPE_MASK 0x3u
> >>> +
> >>> +static void
> >>> +set_age_action_context(void **ctx, enum action_age_context_type
> >>> +type, void *obj) {
> >>> +     uintptr_t value = (uintptr_t)obj;
> >>> +
> >>> +     /*
> >>> +      * obj is allocated by malloc\calloc which must return an address
> >>> +      * aligned to 8.
> >>> +      * Use the last 2 bits for the age context type.
> >>> +      */
> >>> +     value |= (uintptr_t)type & AGE_ACTION_TYPE_MASK;
> >>> +     *ctx = (void *)value;
> >>
> >> Thanks Matan, I think this is much clear. But I though the 'id' will
> >> be used, not the pointer itself, like "uintptr_t value = id | (type * MASK)"
> >> OR the address pointer and type seems error prone, although you
> >> comment you rely on the alignment.
> >
> > I understand your concern, that's why the context value management is
> wrapped well by dedicated functions for set and parse.
> > Also it's very optimized way for memory and time especially when we are
> talking about big scale(see below).
> >
> >> The testpmd usage also kind of sample usage for the applications, I
> >> am for not suggesting this for the user applications.
> >
> >
> >> Reserving the two bit of the 'id' reduces the usable 'id' to 30 bits,
> >> but it looks still big enough, what do you think?
> >
> >
> > Yes, it is big enough.
> > The problem with the id is the latency to get the pointer from it.
> > Since both the flows and the shared actions are saved in a list we need to
> traverse all the list in order to get the pointer and the needed information.
> >
> 
> Using 'id' was your idea.

Yes, Now I suggest even better one 😊

> 
> OK, what about back to previous suggestion, adding a new data struct for both
> pointers and type?
> Your concern there was the memory consumption, yes although it will require
> more memory the amount is not unreasonable.

Think about big scale.
It is not only memory (malloc overhead + ~16B) but also time consuming(malloc).

If we have solution that no need malloc and can do things faster, why not to take it?
I don't see here a bug - malloc alignment is a known topic - it should be at least the size of the biggest primitive type.

Matan