[dpdk-dev] [PATCH v3 0/2] add support for buffered tx to ethdev

[Tomasz Kulasek]

Many sample apps include internal buffering for single-packet-at-a-time
operation. Since this is such a common paradigm, this functionality is
better suited to being implemented in the ethdev API.

The new APIs in the ethdev library are:
* rte_eth_tx_buffer_init - initialize buffer
* rte_eth_tx_buffer - buffer up a single packet for future transmission
* rte_eth_tx_buffer_flush - flush any unsent buffered packets
* rte_eth_tx_buffer_set_err_callback - set up a callback to be called in
  case transmitting a buffered burst fails. By default, we just free the
  unsent packets.

As well as these, an additional reference callbacks are provided, which
frees the packets:

* rte_eth_tx_buffer_drop_callback - silently drop packets (default
  behavior)
* rte_eth_tx_buffer_count_callback - drop and update user-provided counter
  to track the number of dropped packets

Due to the feedback from mailing list, that buffer management facilities
in the user application are more preferable than API simplicity, we decided
to move internal buffer table, as well as callback functions and user data,
from rte_eth_dev/rte_eth_dev_data to the application space.
It prevents ABI breakage and gives some more flexibility in the buffer's
management such as allocation, dynamical size change, reuse buffers on many
ports or after fail, and so on.


The following steps illustrate how tx buffers can be used in application:

1) Initialization

a) Allocate memory for a buffer

   struct rte_eth_dev_tx_buffer *buffer = rte_zmalloc_socket("tx_buffer",
           RTE_ETH_TX_BUFFER_SIZE(MAX_PKT_BURST), 0, socket_id);

   RTE_ETH_TX_BUFFER_SIZE(size) macro computes memory required to store
   "size" packets in buffer.

b) Initialize allocated memory and set up default values. Threshold level
   must be lower than or equal to the MAX_PKT_BURST from 1a)

   rte_eth_tx_buffer_init(buffer, threshold);


c) Set error callback (optional)

   rte_eth_tx_buffer_set_err_callback(buffer, callback_fn, userdata);


2) Store packet "pkt" in buffer and send them all to the queue_id on
   port_id when number of packets reaches threshold level set up in 1b)

   rte_eth_tx_buffer(port_id, queue_id, buffer, pkt);


3) Send all stored packets to the queue_id on port_id

   rte_eth_tx_buffer_flush(port_id, queue_id, buffer);


4) Flush buffer and free memory

   rte_eth_tx_buffer_flush(port_id, queue_id, buffer);
   ...
   rte_free(buffer);

v3 changes:
 - error counter removed from tx buffer structure, now default behavior is
   silent drop of unsent packets
 - some names was changed in tx buffer structure to be more descriptive
 - two default calbacks are provided: rte_eth_tx_buffer_drop_callback and
   rte_eth_tx_buffer_count_callback

v2 changes:
 - reworked to use new buffer model
 - buffer data and callbacks are removed from rte_eth_dev/rte_eth_dev_data,
   so this patch doesn't brake an ABI anymore
 - introduced RTE_ETH_TX_BUFFER macro and rte_eth_tx_buffer_init
 - buffers are not attached to the port-queue
 - buffers can be allocated dynamically during application work
 - size of buffer can be changed without port restart

Tomasz Kulasek (2):
  ethdev: add buffered tx api
  examples: rework to use buffered tx

 examples/l2fwd-jobstats/main.c                     |  104 ++++------
 examples/l2fwd-keepalive/main.c                    |  100 ++++------
 examples/l2fwd/main.c                              |  104 ++++------
 examples/l3fwd-acl/main.c                          |   92 ++++-----
 examples/l3fwd-power/main.c                        |   89 ++++-----
 examples/link_status_interrupt/main.c              |  107 ++++------
 .../client_server_mp/mp_client/client.c            |  101 ++++++----
 examples/multi_process/l2fwd_fork/main.c           |   97 ++++-----
 examples/packet_ordering/main.c                    |  122 ++++++++----
 examples/qos_meter/main.c                          |   61 ++----
 lib/librte_ether/rte_ethdev.c                      |   46 +++++
 lib/librte_ether/rte_ethdev.h                      |  205 +++++++++++++++++++-
 lib/librte_ether/rte_ether_version.map             |   10 +
 13 files changed, 696 insertions(+), 542 deletions(-)

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1.7.9.5