+The application supports two modes of operation: poll mode and event mode.
+
+* In the poll mode a core receives packets from statically configured list
+ of eth ports and eth ports' queues.
+
+* In the event mode a core receives packets as events. After packet processing
+ is done core submits them back as events to an event device. This enables
+ multicore scaling and HW assisted scheduling by making use of the event device
+ capabilities. The event mode configuration is predefined. All packets reaching
+ given eth port will arrive at the same event queue. All event queues are mapped
+ to all event ports. This allows all cores to receive traffic from all ports.
+ Since the underlying event device might have varying capabilities, the worker
+ threads can be drafted differently to maximize performance. For example, if an
+ event device - eth device pair has Tx internal port, then application can call
+ rte_event_eth_tx_adapter_enqueue() instead of regular rte_event_enqueue_burst().
+ So a thread which assumes that the device pair has internal port will not be the
+ right solution for another pair. The infrastructure added for the event mode aims
+ to help application to have multiple worker threads by maximizing performance from
+ every type of event device without affecting existing paths/use cases. The worker
+ to be used will be determined by the operating conditions and the underlying device
+ capabilities. **Currently the application provides non-burst, internal port worker
+ threads and supports inline protocol only.** It also provides infrastructure for
+ non-internal port however does not define any worker threads.
+
+Additionally the event mode introduces two submodes of processing packets:
+
+* Driver submode: This submode has bare minimum changes in the application to support
+ IPsec. There are no lookups, no routing done in the application. And for inline
+ protocol use case, the worker thread resembles l2fwd worker thread as the IPsec
+ processing is done entirely in HW. This mode can be used to benchmark the raw
+ performance of the HW. The driver submode is selected with --single-sa option
+ (used also by poll mode). When --single-sa option is used in conjution with event
+ mode then index passed to --single-sa is ignored.
+
+* App submode: This submode has all the features currently implemented with the
+ application (non librte_ipsec path). All the lookups, routing follows existing
+ methods and report numbers that can be compared against regular poll mode
+ benchmark numbers.