From: Ferruh Yigit <ferruh.yigit@intel.com>
To: Ansar Kannankattil <ansarkannankat@gmail.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>, <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 10:43:03 +0000 [thread overview]
Message-ID: <1a04cc13-8201-4c10-fcb0-bae86c18b4b3@intel.com> (raw)
In-Reply-To: <CAPA_rBcKPFkBomMRr0-dPuTEZi32Dp_rA-QaqN_KwUxsWErTJA@mail.gmail.com>
On 2/10/2022 10:37 AM, Ansar Kannankattil wrote:
moved down, please avoid top post
> On Thu, Feb 10, 2022 at 2:26 PM Ferruh Yigit <ferruh.yigit@intel.com <mailto:ferruh.yigit@intel.com>> wrote:
>
> 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 <mailto: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.
>
>
> Thanks for the responses,
> Then what is the advantage of chaining mbuffs over using the mbuff array?
>
If you have small packet buffer, mbufs can be chained to represent a big packet.
Or scattered buffers can be used to represent a packet by chaining.
Array is used to represent different packets.
next prev parent reply other threads:[~2022-02-10 10:43 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
2022-02-10 10:37 ` Ansar Kannankattil
2022-02-10 10:43 ` Ferruh Yigit [this message]
2022-02-10 11:36 ` Bruce Richardson
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