Re: [dpdk-dev] [ 2nd try ] Lookup mechanim in DPDK HASH table.

["Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>]

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Singh, Jasvinder
> Sent: Monday, August 17, 2015 7:14 PM
> To: Yeddula, Avinash; Richardson, Bruce
> Cc: dev@dpdk.org; Bly, Mike
> Subject: Re: [dpdk-dev] [ 2nd try ] Lookup mechanim in DPDK HASH table.
> 
> Hi,
> 
> > -----Original Message-----
> > From: Yeddula, Avinash [mailto:ayeddula@ciena.com]
> > Sent: Monday, August 17, 2015 5:35 PM
> > To: Singh, Jasvinder; Richardson, Bruce
> > Cc: dev@dpdk.org; Bly, Mike
> > Subject: RE: [dpdk-dev] [ 2nd try ] Lookup mechanim in DPDK HASH table.
> >
> > + Mike ( My team mate)
> > Hi Jasvinder, It's not a bidirectional packet flow. The pipeline looks
> something
> > like this.
> >
> > Ingress port-----Table 1 ----Table-2 ----- Mac_Table ----- Table4 ---- Egress
> > port.
> >
> > Before the frame goes reaches table 4, we do 2 lookups at the mac table.
> > 1. src lookup ( To learn the MAC on the bridge) 2. dst lookup ( Flooding if
> dst
> > MAC look up fails else Unicast/forward if dst lookup success).
> >
> > Here are the keys we are using.
> > Src lookup key  -  Src MAC (src MAC in the frame) + Bridge ID ( Bridge on
> > which it arrived).
> > Dst lookup key  - Dst MAC (dst MAC in the frame) + Bridge ID ( Bridge on
> > which it arrived)
> >
> 
> There is as such no mechanism to support double lookup on the same table
> for the packet. However, alternative approach could be-    first perform
> destination lookup and  invoke action handler ( in both table hit & miss case).
> In action handler, Src MAC + bridge ID key can be added to the table
> (rte_pipeline_table_entry_add) .  If a new entry is successfully added to the
> hash for the specified key, or there is already an entry in the hash for the
> specified key, then the position of the entry is returned. In this way, table
> entries will be updated with incoming packets.
> 

Yes, the two lookups are really one lookup and one add/update operation.

>
> > Thanks
> > -Avinash
> >
> > -----Original Message-----
> > From: Singh, Jasvinder [mailto:jasvinder.singh@intel.com]
> > Sent: Monday, August 17, 2015 7:00 AM
> > To: Richardson, Bruce; Yeddula, Avinash
> > Cc: dev@dpdk.org
> > Subject: RE: [dpdk-dev] [ 2nd try ] Lookup mechanim in DPDK HASH table.
> >
> >
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce
> Richardson
> > > Sent: Friday, August 14, 2015 10:25 AM
> > > To: Yeddula, Avinash
> > > Cc: dev@dpdk.org
> > > Subject: Re: [dpdk-dev] [ 2nd try ] Lookup mechanim in DPDK HASH table.
> > >
> > > On Thu, Aug 13, 2015 at 05:37:21PM -0400, Yeddula, Avinash wrote:
> > > > Any comments on this question ?
> > > >
> > > > Thanks
> > > > -Avinash
> > > >
> > > > -----Original Message-----
> > > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Yeddula,
> > > > Avinash
> > > > Sent: Wednesday, August 12, 2015 3:04 PM
> > > > To: dev@dpdk.org
> > > > Subject: [dpdk-dev] Lookup mechanim in DPDK HASH table.
> > > >
> > > > Hello All,
> > > >
> > > > I'm using DPDK extendable hash tables. This question is with respect
> > > > to the
> > > lookup aspect of the hash table.
> > > > I see that there is just one "t->key_offset" that is pre-defined for
> > > > the hash
> > > table. I also understand that the frame needs to carry the "lookup_key
> > > / keys" in the meta data.
> > > >
> > > > Here is my question:  How to support more than one lookup with
> > > > different
> > > keys on the same frame on the same table.
> > > > Use case: Src mac  lookup and dst mac lookup on the same mac table.
> > > >
> > > > Thanks
> > > > -Avinash
> > >
> > > Just to confirm: this is using the extensible bucket hash in the
> > > rte_table library of packet framework, rather than the standalone
> > > rte_hash library, right?
> > >
> > > /Bruce
> >
> > Could you share detail on the two different keys used for lookups. In case if
> > you are considering bidirectional packet flow between the source and
> > destination, symmetric hash can be used-
> > http://www.ndsl.kaist.edu/~kyoungsoo/papers/TR-symRSS.pdf
> >
> > Jasvinder