[dpdk-dev] Requirement of minimum Rx burst size for PMDs

Bruce Richardson bruce.richardson at intel.com
Fri Oct 20 13:58:23 CEST 2017


On Fri, Oct 20, 2017 at 01:07:17PM +0300, Andrew Rybchenko wrote:
> On 10/20/2017 04:18 AM, Yongseok Koh wrote:
> > Therefore, how about adding min_rx/tx_burst_sz in struct rte_eth_dev_info and
> > have PMDs fill it in on dev_ops->dev_infos_get() so as to make apps comply with
> > it.
> 
> Just for my understand, what should happen if application wants to send only
> one packet? 5 packets? 33? 35?

I actually think there is a mistake in the original mails. At least for
Intel PMDs there is no restriction on min TX burst sizes in any code
path. The vector RX on the other hand does require a minimum number of empty
buffers to be passed to it, so you need to request no fewer than 4
packets in a burst. If only one packet is available that will still be
returned to you, but you must request at least 4 

Reagrds,
/Bruce


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