== OpenDataPlane (1.21.0.0)

=== Summary of Changes
ODP v1.21.0.0 adds two new API families as well as several small improvements.

==== APIs
===== Compression Support
A new family of APIs is added that provides for session-oriented support for
packet data compression and decompression. Compression sessions define the
parameters used to control compression operations and their associated
integrity hashes.  Once created, sessions are input parameters to the new
`odp_comp_op()` and `odp_comp_op_enq()` APIs that provide access to
synchronous and asynchronous compression services on packets.

Associated with the completion of asynchronous compression operations, a new
packet subtype, `ODP_EVENT_PACKET_COMP` is defined. This subtype indicates
that the packet includes additional metadata (retrievable via
`odp_comp_result()`) that provides the result of the requested operation.

A number of different compression and associated hash algorithms are defined,
which are communicated with three new capability APIs:

`odp_comp_capability()`::
Provides information about general compression related capabilities
offered by this implementation

`odp_comp_alg_capability()`::
Provides details about the capabilities of individual compression algorithms
supported.

`odp_comp_hash_alg_capability()`::
Provides details about the capabilities of individual hash algorithms
supported for use with compression.

===== Flow Aware Scheduler Support
A new capability for flow aware scheduling is added. As part of this, the
scheduler now supports capabilities and configurability. As a result, the
initialization sequence for applications that make use of the ODP scheduler
has changed slightly. The new API call sequence is:
[source,c]
-----
odp_schedule_capability()
odp_schedule_config_init()
odp_schedule_config()
odp_schedule()
-----
It is a programming error to call `odp_schedule()` (or its variants) without
having first initialized the scheduler with an `odp_schedule_config()` call.
This call may only be issued once per ODP instance as scheduler configuration
is global.

By default the scheduler operates as before. When configured to operate in
flow aware mode, the scheduler will now respect event flow ids (managed by the
new `odp_event_flow_id()` and `odp_event_flow_id_set()` APIs) when making
scheduling decisions. This means that flow identification is a combination of
event flow id and queue id. For example, when operating in flow aware mode the
scheduler may dispatch events from an atomic queue to multiple threads
concurrently, as long as those events have different flow ids. For
applications that process large numbers of lightweight flows that have limited
context needs, this can lead to throughput improvements as well as reduced
implementation memory footprint.

==== DPDK v18.11 Support
The latest LTS release of DPDK (v18.11) is now supported by ODP. Support for
the previous LTS release (v17.11) is retained. Prior versions of DPDK are
no longer supported.

==== Queue Capabilities Moved to Scheduler
As part of the introduction of flow-aware scheduling, capabilities associated
with `SCHED` queues have been moved from the `odp_queue_capabilities_t` struct
returned by `odp_queue_capabilities()` to the new `odp_sched_capabilities_t`
struct returned by `odp_sched_capabilities()`.

Capabilities moved include `max_ordered_locks`, `max_sched_groups`, and
`sched_prios`. The `max_sched_groups` capability is renamed `max_groups`. In
addition, `max_queues`, `max_queue_size`, and the support capabilities for
lock free and wait free non blocking queues is now part of the scheduler
capabilities.

In support of flow aware scheduling mode, the `max_flows` scheduler capability
is renamed `max_flow_id`. A value of 0 indicates that flow aware mode
scheduling is not available in this ODP implementation.

=== Test/Validation Improvements
==== Travis readability improvement
The "BUILD_ONLY` environment variable has been renamed `CHECK` for improved
output readability.

==== Flow aware scheduler testing
As part of flow aware mode, scheduler validation tests will now test this mode
if `odp_schedule_capability()` indicates that flow-aware mode is supported.

=== Bug Fixes
==== Unnumbered Bugs/Issues

* Latest version of netmap `nm_ring_empty()` implementation has changed.
PktIO netmap support updated to support this as well as previous releases.

* Improved compatibility of PktIO socket support with latest versions
of the clang compiler.

* Add match pattern for missing DPDK PMD drivers for improved compatibility.