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ethdev: add API to free consumed buffers in Tx ring

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Add a new API to force free consumed buffers on Tx ring. API will return
the number of packets freed (0-n) or error code if feature not supported
(-ENOTSUP) or input invalid (-ENODEV).

Signed-off-by: Billy McFall <bmcfall@redhat.com>
Acked-by: Keith Wiles <keith.wiles@intel.com>
This commit is contained in:
Billy McFall 2017-03-24 14:55:53 -04:00 committed by Thomas Monjalon
parent ac71108d64
commit 44a718c457
6 changed files with 96 additions and 3 deletions
doc/guides
conf.py
nics/features
default.ini
prog_guide
poll_mode_drv.rst
rel_notes
release_17_05.rst
lib/librte_ether
rte_ethdev.crte_ethdev.h

7
doc/guides/conf.py

@ -64,6 +64,9 @@ release = version
master_doc = 'index'
# Maximum feature description string length
feature_str_len = 25
# Figures, tables and code-blocks automatically numbered if they have caption
numfig = True
@ -300,7 +303,7 @@ def print_table_body(outfile, num_cols, ini_files, ini_data, default_features):
def print_table_row(outfile, feature, line):
""" Print a single row of the table with fixed formatting. """
line = line.rstrip()
print(' {:<20}{}'.format(feature, line), file=outfile)
print(' {:<{}}{}'.format(feature, feature_str_len, line), file=outfile)
def print_table_divider(outfile, num_cols):
@ -309,7 +312,7 @@ def print_table_divider(outfile, num_cols):
column_dividers = ['='] * num_cols
line += ' '.join(column_dividers)
feature = '=' * 20
feature = '=' * feature_str_len
print_table_row(outfile, feature, line)

4
doc/guides/nics/features/default.ini

@ -3,7 +3,8 @@
;
; This file defines the features that are valid for inclusion in
; the other driver files and also the order that they appear in
; the features table in the documentation.
; the features table in the documentation. The feature description
; string should not exceed feature_str_len defined in conf.py.
;
[Features]
Speed capabilities =
@ -11,6 +12,7 @@ Link status =
Link status event =
Queue status event =
Rx interrupt =
Free Tx mbuf on demand =
Queue start/stop =
MTU update =
Jumbo frame =

36
doc/guides/prog_guide/poll_mode_drv.rst

@ -249,6 +249,42 @@ One descriptor in the TX ring is used as a sentinel to avoid a hardware race con
When configuring for DCB operation, at port initialization, both the number of transmit queues and the number of receive queues must be set to 128.
Free Tx mbuf on Demand
~~~~~~~~~~~~~~~~~~~~~~
Many of the drivers do not release the mbuf back to the mempool, or local cache,
immediately after the packet has been transmitted.
Instead, they leave the mbuf in their Tx ring and
either perform a bulk release when the ``tx_rs_thresh`` has been crossed
or free the mbuf when a slot in the Tx ring is needed.
An application can request the driver to release used mbufs with the ``rte_eth_tx_done_cleanup()`` API.
This API requests the driver to release mbufs that are no longer in use,
independent of whether or not the ``tx_rs_thresh`` has been crossed.
There are two scenarios when an application may want the mbuf released immediately:
* When a given packet needs to be sent to multiple destination interfaces
(either for Layer 2 flooding or Layer 3 multi-cast).
One option is to make a copy of the packet or a copy of the header portion that needs to be manipulated.
A second option is to transmit the packet and then poll the ``rte_eth_tx_done_cleanup()`` API
until the reference count on the packet is decremented.
Then the same packet can be transmitted to the next destination interface.
The application is still responsible for managing any packet manipulations needed
between the different destination interfaces, but a packet copy can be avoided.
This API is independent of whether the packet was transmitted or dropped,
only that the mbuf is no longer in use by the interface.
* Some applications are designed to make multiple runs, like a packet generator.
For performance reasons and consistency between runs,
the application may want to reset back to an initial state
between each run, where all mbufs are returned to the mempool.
In this case, it can call the ``rte_eth_tx_done_cleanup()`` API
for each destination interface it has been using
to request it to release of all its used mbufs.
To determine if a driver supports this API, check for the *Free Tx mbuf on demand* feature
in the *Network Interface Controller Drivers* document.
Hardware Offload
~~~~~~~~~~~~~~~~

7
doc/guides/rel_notes/release_17_05.rst

@ -41,6 +41,12 @@ New Features
Also, make sure to start the actual text at the margin.
=========================================================
* **Added free Tx mbuf on demand API.**
Added a new function ``rte_eth_tx_done_cleanup()`` which allows an application
to request the driver to release mbufs from their Tx ring that are no longer
in use, independent of whether or not the ``tx_rs_thresh`` has been crossed.
* **Increased number of next hops for LPM IPv6 to 2^21.**
The next_hop field is extended from 8 bits to 21 bits for IPv6.
@ -49,6 +55,7 @@ New Features
sPAPR IOMMU based pci probing enabled for vfio-pci devices.
Resolved Issues
---------------

14
lib/librte_ether/rte_ethdev.c

@ -1275,6 +1275,20 @@ rte_eth_tx_buffer_init(struct rte_eth_dev_tx_buffer *buffer, uint16_t size)
return ret;
}
int
rte_eth_tx_done_cleanup(uint8_t port_id, uint16_t queue_id, uint32_t free_cnt)
{
struct rte_eth_dev *dev = &rte_eth_devices[port_id];
/* Validate Input Data. Bail if not valid or not supported. */
RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->tx_done_cleanup, -ENOTSUP);
/* Call driver to free pending mbufs. */
return (*dev->dev_ops->tx_done_cleanup)(dev->data->tx_queues[queue_id],
free_cnt);
}
void
rte_eth_promiscuous_enable(uint8_t port_id)
{

31
lib/librte_ether/rte_ethdev.h

@ -1183,6 +1183,9 @@ typedef int (*eth_fw_version_get_t)(struct rte_eth_dev *dev,
char *fw_version, size_t fw_size);
/**< @internal Get firmware information of an Ethernet device. */
typedef int (*eth_tx_done_cleanup_t)(void *txq, uint32_t free_cnt);
/**< @internal Force mbufs to be from TX ring. */
typedef void (*eth_rxq_info_get_t)(struct rte_eth_dev *dev,
uint16_t rx_queue_id, struct rte_eth_rxq_info *qinfo);
@ -1488,6 +1491,7 @@ struct eth_dev_ops {
eth_rx_disable_intr_t rx_queue_intr_disable; /**< Disable Rx queue interrupt. */
eth_tx_queue_setup_t tx_queue_setup;/**< Set up device TX queue. */
eth_queue_release_t tx_queue_release; /**< Release TX queue. */
eth_tx_done_cleanup_t tx_done_cleanup;/**< Free tx ring mbufs */
eth_dev_led_on_t dev_led_on; /**< Turn on LED. */
eth_dev_led_off_t dev_led_off; /**< Turn off LED. */
@ -3177,6 +3181,33 @@ void
rte_eth_tx_buffer_count_callback(struct rte_mbuf **pkts, uint16_t unsent,
void *userdata);
/**
* Request the driver to free mbufs currently cached by the driver. The
* driver will only free the mbuf if it is no longer in use. It is the
* application's responsibity to ensure rte_eth_tx_buffer_flush(..) is
* called if needed.
*
* @param port_id
* The port identifier of the Ethernet device.
* @param queue_id
* The index of the transmit queue through which output packets must be
* sent.
* The value must be in the range [0, nb_tx_queue - 1] previously supplied
* to rte_eth_dev_configure().
* @param free_cnt
* Maximum number of packets to free. Use 0 to indicate all possible packets
* should be freed. Note that a packet may be using multiple mbufs.
* @return
* Failure: < 0
* -ENODEV: Invalid interface
* -ENOTSUP: Driver does not support function
* Success: >= 0
* 0-n: Number of packets freed. More packets may still remain in ring that
* are in use.
*/
int
rte_eth_tx_done_cleanup(uint8_t port_id, uint16_t queue_id, uint32_t free_cnt);
/**
* The eth device event type for interrupt, and maybe others in the future.
*/