Re: [RFC] eventdev: add crypto adapter API header

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Wed, 13 Dec 2017 23:35:48 +0000
> From: "Eads, Gage" <gage.eads@intel.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, "Gujjar, Abhinandan S"
>  <abhinandan.gujjar@intel.com>
> CC: "dev@dpdk.org" <dev@dpdk.org>, "Vangati, Narender"
>  <narender.vangati@intel.com>, "Rao, Nikhil" <nikhil.rao@intel.com>,
>  "hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>, "Doherty, Declan"
>  <declan.doherty@intel.com>, "nidadavolu.murthy@cavium.com"
>  <nidadavolu.murthy@cavium.com>, "nithin.dabilpuram@cavium.com"
>  <nithin.dabilpuram@cavium.com>, "narayanaprasad.athreya@cavium.com"
>  <narayanaprasad.athreya@cavium.com>
> Subject: RE: [RFC] eventdev: add crypto adapter API header
> 
> Hey Jerin,

Hey Gage,

> 
> </snip>
> 
> > > +
> > > + /**
> > > + * @warning
> > > + * @b EXPERIMENTAL: this enum may change without prior notice
> > > + *
> > > + * Crypto event adapter type
> > > + */
> > > +enum rte_event_crypto_adapter_type {
> > > +	RTE_EVENT_CRYPTO_ADAPTER_RX_ONLY = 1,
> > > +	/**< Start only Rx part of crypto adapter.
> > > +	* Packets dequeued from cryptodev are new to eventdev and
> > > +	* events will be treated as RTE_EVENT_OP_NEW */
> > > +	RTE_EVENT_CRYPTO_ADAPTER_RX_TX,
> > > +	/**< Start both Rx & Tx part of crypto adapter.
> > > +	* Packet's event context will be retained and
> > > +	* event will be treated as RTE_EVENT_OP_FORWARD */ };
> > 
> > How about leveraging ev.op based schematics as mentioned above?
> 
> That could work, but perhaps the ev.op should be configured once up front, as I see it being a function of the application architecture. A couple possible designs, for example:
> - Worker enqueues into cryptodev, adapter polls for response: the adapter port would always use OP_NEW here.
> - Worker sends a crypto request event to the adapter, which gives the request to the cryptodev and polls for response: the adapter port would always use OP_FWD here. (This ties in with my implicit release patch (http://dpdk.org/ml/archives/dev/2017-December/083535.html))
> - Etc.

Yes. Semantically both approaches will work. I was trying to avoid extra
clutter(enum rte_event_crypto_adapter_type) in adapter API.
I don't see any problem in moving ev.op to adapter configuration time if it
helps the SW driver.

IMO, We can change RTE_EVENT_CRYPTO_ADAPTER_RX_ONLY and
RTE_EVENT_CRYPTO_ADAPTER_RX_TX to more appropriate name, something like,
RTE_EVENT_CRYPTO_ADAPTER_TYPE_OP_NEW/RTE_EVENT_CRYPTO_ADAPTER_TYPE_OP_FWD
or something like that.


> 
> So I think it makes sense to specify the op once at adapter configuration time, rather than repeatedly in the datapath. This allows for a cleaner separation of configuration and datapath code, and specifying it just once means fewer chances to accidentally set the wrong op value.
> 
> Thanks,
> Gage