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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> 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(-)
> 
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 1.7.9.5