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From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Ansar Kannankattil <ansarkannankat@gmail.com>, <dev@dpdk.org>
Subject: Re: Can I use rte_pktmbuf_chain to chain multiple mbuffs for calling only single tx_eth_burst API
Date: Thu, 10 Feb 2022 08:56:25 +0000	[thread overview]
Message-ID: <7dccdaf8-10d0-69f2-2a91-791dde993cee@intel.com> (raw)
In-Reply-To: <20220209144617.79834bd6@hermes.local>

On 2/9/2022 10:46 PM, Stephen Hemminger wrote:
> On Wed, 9 Feb 2022 22:18:24 +0000
> Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> 
>> On 2/9/2022 6:03 PM, Ansar Kannankattil wrote:
>>> Hi
>>> My intention is to decrease the number of rte_tx_eth_burst calls, I know that mentioning nb_pkts will result in sending multiple packets in a single call.
>>> But providing nb_pkts=1 and posting a head mbuff having number of mbuffs linked with it will results sending multiple packets
>>
>> If driver supports, you can do it.
>> Driver should expose this capability via RTE_ETH_TX_OFFLOAD_MULTI_SEGS flag,
>> in 'dev_info->tx_offload_capa'.
>>
>>> If not, what is the use case of linking multiple mbuffs together
>>
>> It is also used in Rx path (again if driver supports).
> 
> I think Ansar was asking about chaining multiple packets in one call to tx burst.
> The chaining in DPDK is to make a single packet out of multiple pieces (like writev).
> 
> DPDK mbufs were based on original BSD concept.
> In BSD mbufs, mbuf has two linked lists.
>    BSD m->m_next pointer == DPDK m->next  for multiple parts of packet.
>    BSD m->m_nextpkt                       for next packet in queue
> 
> There is no nextpkt in DPDK.

Right, chaining mbufs is for segmented packets.

  reply	other threads:[~2022-02-10  8:56 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-09 18:03 Ansar Kannankattil
2022-02-09 20:56 ` Stephen Hemminger
2022-02-09 22:18 ` Ferruh Yigit
2022-02-09 22:46   ` Stephen Hemminger
2022-02-10  8:56     ` Ferruh Yigit [this message]
2022-02-10 10:37       ` Ansar Kannankattil
2022-02-10 10:43         ` Ferruh Yigit
2022-02-10 11:36         ` Bruce Richardson

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