[dpdk-dev] [PATCH] config: increase default maximum number of NUMA nodes

[Thomas Monjalon]

04/02/2021 07:19, Jerin Jacob:
> On Thu, Feb 4, 2021 at 2:49 AM Thomas Monjalon <thomas at monjalon.net> wrote:
> >
> > AMD CPU can present a high number of NUMA nodes.
> > The default should be 32 for better compatibility.
> 
> The typical configuration is 4 nodes[1] for AMD. Just wondering, Is it
> an exception case? if so, Do we need to consume more memory for normal
> cases?
> 
> [1]
> https://developer.amd.com/wp-content/resources/56308-NUMA%20Topology%20for%20AMD%20EPYC%E2%84%A2%20Naples%20Family%20Processors.PDF

As you can read in
https://www.dell.com/support/kbdoc/fr-fr/000137696/amd-rome-is-it-for-real-architecture-and-initial-hpc-performance
there is an option "CCX as NUMA Domain.
This option exposes each CCX as a NUMA node.
On a system with dual-socket CPUs with 16 CCXs per CPU,
this setting will expose 32 NUMA domains."
and
"Enabling this option is expected to help virtualized environments."

I would not say it is exceptional.
And in my understanding, the memory cost is not so high for DPDK.
Do you see some large arrays depending on RTE_MAX_NUMA_NODES?