Re: [dpdk-dev] [RFC v2, 2/2] eventdev: add crypto adapter API header

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

-----Original Message-----
> Date: Mon, 19 Feb 2018 10:55:58 +0000
> From: "Gujjar, Abhinandan S" <abhinandan.gujjar@intel.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> CC: "dev@dpdk.org" <dev@dpdk.org>, "Vangati, Narender"
>  <narender.vangati@intel.com>, "Rao, Nikhil" <nikhil.rao@intel.com>, "Eads,
>  Gage" <gage.eads@intel.com>, "hemant.agrawal@nxp.com"
>  <hemant.agrawal@nxp.com>, "akhil.goyal@nxp.com" <akhil.goyal@nxp.com>,
>  "narayanaprasad.athreya@cavium.com" <narayanaprasad.athreya@cavium.com>,
>  "nidadavolu.murthy@cavium.com" <nidadavolu.murthy@cavium.com>,
>  "nithin.dabilpuram@cavium.com" <nithin.dabilpuram@cavium.com>
> Subject: RE: [RFC v2, 2/2] eventdev: add crypto adapter API header
> 
> Hi Jerin,

Hi Abhinandan,

> 
> Thanks for the review. Please find few comments inline.
> 
> > -----Original Message-----
> > From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
> > Sent: Saturday, February 17, 2018 1:04 AM
> > To: Gujjar, Abhinandan S <abhinandan.gujjar@intel.com>
> > Cc: dev@dpdk.org; Vangati, Narender <narender.vangati@intel.com>; Rao,
> > Nikhil <nikhil.rao@intel.com>; Eads, Gage <gage.eads@intel.com>;
> > hemant.agrawal@nxp.com; akhil.goyal@nxp.com;
> > narayanaprasad.athreya@cavium.com; nidadavolu.murthy@cavium.com;
> > nithin.dabilpuram@cavium.com
> > Subject: Re: [RFC v2, 2/2] eventdev: add crypto adapter API header
> > 
> > -----Original Message-----
> > > Date: Mon, 15 Jan 2018 16:23:50 +0530
> > > From: Abhinandan Gujjar <abhinandan.gujjar@intel.com>
> > > To: jerin.jacob@caviumnetworks.com
> > > CC: dev@dpdk.org, narender.vangati@intel.com, Abhinandan Gujjar
> > > <abhinandan.gujjar@intel.com>, Nikhil Rao <nikhil.rao@intel.com>, Gage
> > > Eads <gage.eads@intel.com>
> > > Subject: [RFC v2, 2/2] eventdev: add crypto adapter API header
> > > X-Mailer: git-send-email 1.9.1
> > >
> > > +
> > > +/**
> > > + * This adapter adds support to enqueue crypto completions to event device.
> > > + * The packet flow from cryptodev to the event device can be
> > > +accomplished
> > > + * using both SW and HW based transfer mechanisms.
> > > + * The adapter uses a EAL service core function for SW based packet
> > > +transfer
> > > + * and uses the eventdev PMD functions to configure HW based packet
> > > +transfer
> > > + * between the cryptodev and the event device.
> > > + *
> > > + * In the case of SW based transfers, application can choose to
> > > +submit a
> > 
> > I think, we can remove "In the case of SW based transfers" as it should be
> > applicable for HW case too
> Ok. In that case, adapter will detect the presence of HW connection between
> cryptodev & eventdev and will not dequeue crypto completions.

I would say presence of "specific capability" instead of HW.

> 
> > 
> > > + * crypto operation directly to cryptodev or send it  to the
> > > + cryptodev
> > > + * adapter via eventdev, the cryptodev adapter then submits the
> > > + crypto
> > > + * operation to the crypto device. The first mode is known as the
> > 
> > The first mode (DEQ) is very clear. In the second mode(ENQ_DEQ),
> > - How does "worker" submits the crypto work through crypto-adapter?
> > If I understand it correctly, "workers" always deals with only cryptodev's
> > rte_cryptodev_enqueue_burst() API and "service" function in crypto adapter
> > would be responsible for dequeue() from cryptodev and enqueue to eventdev?
> > 
> > I understand the need for OP_NEW vs OP_FWD mode difference in both modes.
> > Other than that, What makes ENQ_DEQ different? Could you share the flow for
> > ENQ_DEQ mode with APIs.
> 
> /*
> Application changes for ENQ_DEQ mode:
> -------------------------------------------------
> 	/* In ENQ_DEQ mode, to enqueue to adapter app
> 	 * has to fill out following details.
> 	 */
> 	struct rte_event_crypto_request *req;
> 	struct rte_crypto_op *op = rte_crypto_op_alloc();
> 	
> 	/* fill request info */
> 	req = (void *)((char *)op + op.private_data_offset);
> 	req->cdev_id = 1;
> 	req->queue_pair_id = 1;
> 
> 	/* fill response info */
> 	...
> 
> 	/* send event to crypto adapter */
> 	ev->event_ptr = op;
> 	ev->queue_id = dst_event_qid;
> 	ev->priority = dst_priority;
> 	ev->sched_type = dst_sched_type;
> 	ev->event_type = RTE_EVENT_TYPE_CRYPTODEV;
> 	ev->sub_event_type = sub_event_type;
> 	ev->flow_id = dst_flow_id;
> 	ret = rte_event_enqueue_burst(event_dev_id, event_port_id, ev, 1);
> 
> 
> Adapter in ENQ_DEQ mode, submitting crypto ops to cryptodev:
> -----------------------------------------------------------------------------
> 	n = rte_event_dequeue_burst(event_dev_id, event_port_id, ev, BATCH_SIZE, time_out);
> 	struct rte_crypto_op *op = ev->event_ptr;
> 	struct rte_event_crypto_request *req = (void *)op + op.private_data_offset;
> 	cdev_id = req->cdev_id;
> 	qp_id = req->queue_pair_id
> 
> 	ret = rte_cryptodev_enqueue_burst(cdev_id, qp_id, op, 1);

This mode wont work for the HW implementations that I know. As in HW
implementations, The Adapter is embedded in HW.
The DEQ mode works. But, This would call for to have two separate application logic for
DEQ and ENQ_DEQ mode.
I think, it is unavoidable as SW scheme has better performance with ENQ_DEQ MODE.

If you think, there is no option other than introducing a capability in
adapter then please create capability in Rx adapter to inform the
adapter capability to the application. 

Do we think, it possible to have scheme with ENQ_DEQ mode, Where
application still enqueue to cryptodev like DEQ mode but using
cryptodev. ie. Adapter patches the cryptodev dev->enqueue_burst() to
"eventdev enqueue burst" followed by "exiting dev->enqueue_burst".
Something like exiting ethdev rx_burst callback scheme.
This will enable application to have unified flow IMO.

Any thoughts from NXP folks?

> */
> > 
> > > + * dequeue only (DEQ) mode  and the second as the enqueue - dequeue
> > 
> > extra space between "mode" and "and"
> Ok
> > 
> > > + * (ENQ_DEQ) mode. The choice of mode can be specified when creating
> > > + * the adapter.
> > > + * In the latter choice, the cryptodev adapter is able to use
> > > + * RTE_OP_FORWARD as the event dev enqueue type, this has a
> > > + performance
> > > + * advantage in "closed system" eventdevs like the eventdev SW PMD
> > > + and
> >