[dpdk-dev] [PATCH 1/3] ethdev: New API to free consumed buffers in TX ring
Stephen Hemminger
stephen at networkplumber.org
Fri Dec 16 17:28:54 CET 2016
On Fri, 16 Dec 2016 07:48:49 -0500
Billy McFall <bmcfall at redhat.com> wrote:
> /**
> + * 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.
> + *
> + * @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.
> + * @param buffer
> + * Buffer used to collect packets to be sent. If provided, the buffer will
> + * be flushed, even if the current length is less than buffer->size. Pass NULL
> + * if buffer has already been flushed.
> + * @param sent
> + * Pointer to return number of packets sent if buffer has packets to be sent.
> + * If *buffer is supplied, *sent must also be supplied.
> + * @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.
> + */
> +
> +static inline int
> +rte_eth_tx_done_cleanup(uint8_t port_id, uint16_t queue_id, uint32_t free_cnt,
> + struct rte_eth_dev_tx_buffer *buffer, uint16_t *sent)
This API is more complex than it needs to be.
For the typical use case of OOM kind of cleanup, this is overkill.
There is no need for:
free_cnt - device driver should just free all
buffer/param - the application should not care.
The DPDK model is that once mbuf's are passed to device, the device "owns"
the mbuf. I think changing that model is just going to break things for
no gain. It does make sense to have a "please cleanup your mbufs" call.
If application is using special mbuf's then it can use the normal callback
on done model.
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