[dpdk-dev] [PATCH v2] mbuf:rearrange mbuf to be more mbuf chain friendly

[Thomas Monjalon]

2016-06-27 10:27, Olivier Matz:
> On 06/27/2016 10:21 AM, Ananyev, Konstantin wrote:
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Keith Wiles
> >> Move the next pointer to the first cacheline of the rte_mbuf structure
> >> and move the offload values to the second cacheline to give better
> >> performance to applications using chained mbufs.
> >>
> >> Enabled by a configuration option CONFIG_RTE_MBUF_CHAIN_FRIENDLY default
> >> is set to No.
> > 
> > First, it would make ixgbe and i40e vector RX functions to work incorrectly.
> > Second, I don't think we can afford to allow people swap mbuf fields in the way they like.
> > Otherwise we'll end-up with totally unmaintainable code pretty soon.
> > So NACK.  
> 
> +1

To be more precise, the arrangement of fields in rte_mbuf is open
to debate and changes.
There is a recent discussion here:
	http://dpdk.org/ml/archives/dev/2016-May/039483.html

I think we must try to improve few things in mbuf during the 16.11 cycle.
But it must not be allowed to have a build option to adapt this structure
or any other API. There is only one DPDK API for a given version.