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.yi...@intel.com <mailto:ferruh.yi...@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.yi...@intel.com <mailto:ferruh.yi...@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.
