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From: Andrew Rybchenko <arybchenko@solarflare.com>
To: Viacheslav Ovsiienko <viacheslavo@mellanox.com>, <dev@dpdk.org>
Cc: <matan@mellanox.com>, <rasland@mellanox.com>,
	<thomas@monjalon.net>, <ferruh.yigit@intel.com>,
	<jerinjacobk@gmail.com>, <stephen@networkplumber.org>,
	<ajit.khaparde@broadcom.com>, <maxime.coquelin@redhat.com>,
	<olivier.matz@6wind.com>, <david.marchand@redhat.com>
Subject: Re: [dpdk-dev] ***Spam*** [PATCH] doc: announce changes to ethdev rxconf structure
Date: Mon, 3 Aug 2020 17:31:03 +0300
Message-ID: <32d6e003-d4e7-06b0-39f3-f4a3ba2b6df6@solarflare.com> (raw)
In-Reply-To: <1596452291-25535-1-git-send-email-viacheslavo@mellanox.com>

On 8/3/20 1:58 PM, Viacheslav Ovsiienko wrote:
> The DPDK datapath in the transmit direction is very flexible.
> The applications can build multisegment packets and manages
> almost all data aspects - the memory pools where segments
> are allocated from, the segment lengths, the memory attributes
> like external, registered, etc.
>
> In the receiving direction, the datapath is much less flexible,
> the applications can only specify the memory pool to configure
> the receiving queue and nothing more. In order to extend the
> receiving datapath capabilities it is proposed to add the new
> fields into rte_eth_rxconf structure:
>
> struct rte_eth_rxconf {
>     ...
>     uint16_t rx_split_num; /* number of segments to split */
>     uint16_t *rx_split_len; /* array of segment lengthes */
>     struct rte_mempool **mp; /* array of segment memory pools */
>     ...
> };
>
> The non-zero value of rx_split_num field configures the receiving
> queue to split ingress packets into multiple segments to the mbufs
> allocated from various memory pools according to the specified
> lengths. The zero value of rx_split_num field provides the
> backward compatibility and queue should be configured in a regular
> way (with single/multiple mbufs of the same data buffer length
> allocated from the single memory pool).

From the above description it is not 100% clear how it will
coexist with:
 - existing mb_pool argument of the rte_eth_rx_queue_setup()
 - DEV_RX_OFFLOAD_SCATTER
 - DEV_RX_OFFLOAD_HEADER_SPLIT
How will application know that the feature is supported? Limitations?
Is it always split by specified/fixed length?
What happens if header length is actually different?

> The new approach would allow splitting the ingress packets into
> multiple parts pushed to the memory with different attributes.
> For example, the packet headers can be pushed to the embedded data
> buffers within mbufs and the application data into the external
> buffers attached to mbufs allocated from the different memory
> pools. The memory attributes for the split parts may differ
> either - for example the application data may be pushed into
> the external memory located on the dedicated physical device,
> say GPU or NVMe. This would improve the DPDK receiving datapath
> flexibility preserving compatibility with existing API.
>
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
> ---
>  doc/guides/rel_notes/deprecation.rst | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
> index ea4cfa7..cd700ae 100644
> --- a/doc/guides/rel_notes/deprecation.rst
> +++ b/doc/guides/rel_notes/deprecation.rst
> @@ -99,6 +99,11 @@ Deprecation Notices
>    In 19.11 PMDs will still update the field even when the offload is not
>    enabled.
>  
> +* ethdev: add new fields to ``rte_eth_rxconf`` to configure the receiving
> +  queues to split ingress packets into multiple segments according to the
> +  specified lengths into the buffers allocated from the specified
> +  memory pools. The backward compatibility to existing API is preserved.
> +
>  * ethdev: ``rx_descriptor_done`` dev_ops and ``rte_eth_rx_descriptor_done``
>    will be deprecated in 20.11 and will be removed in 21.11.
>    Existing ``rte_eth_rx_descriptor_status`` and ``rte_eth_tx_descriptor_status``


  parent reply	other threads:[~2020-08-03 14:31 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-03 10:58 [dpdk-dev] " Viacheslav Ovsiienko
2020-08-03 11:56 ` Jerin Jacob
2020-08-03 13:06   ` Slava Ovsiienko
2020-08-04 13:32     ` Jerin Jacob
2020-08-05  6:35       ` Slava Ovsiienko
2020-08-06 15:58       ` Ferruh Yigit
2020-08-06 16:25         ` Stephen Hemminger
2020-08-06 16:41           ` Jerin Jacob
2020-08-06 17:03           ` Slava Ovsiienko
2020-08-06 18:10             ` Stephen Hemminger
2020-08-07 11:23               ` Slava Ovsiienko
2020-08-03 14:31 ` Andrew Rybchenko [this message]
2020-08-06 16:15   ` Ferruh Yigit
2020-08-06 16:29     ` Slava Ovsiienko
2020-08-06 16:37       ` Ferruh Yigit
2020-08-06 16:39         ` Slava Ovsiienko
2020-08-06 16:43           ` Ferruh Yigit
2020-08-06 16:48             ` Slava Ovsiienko
2020-08-05  8:49 ` [dpdk-dev] [PATCH v2] " Viacheslav Ovsiienko
2020-08-05 11:14   ` Andrew Rybchenko
2020-08-06 12:39     ` Thomas Monjalon
2020-08-06 21:42       ` Thomas Monjalon
2020-08-06 16:31   ` Ferruh Yigit
2020-08-06 17:00     ` Slava Ovsiienko
2020-08-06 16:55   ` [dpdk-dev] [PATCH v2] doc: fix the release notes for Mellanox PMD Viacheslav Ovsiienko
2020-08-06 17:12     ` Asaf Penso
2020-08-06 22:37       ` Thomas Monjalon

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