Re: [PATCH v2] examples/l3fwd: dynamic NUMA-aware alloc lcore_conf

[Thomas Monjalon <thomas@monjalon.net>]

24/06/2026 05:23, Chengwen Feng:
> Currently lcore_conf is a global static array. When multiple
> ports/lcores are distributed across different NUMA nodes, datapath
> suffers from severe cross-NUMA memory access penalty.
> 
> On Kunpeng platform, sizeof(struct lcore_conf) reaches 133760 bytes.
> Such a huge per-lcore structure significantly amplifies cross-NUMA
> overhead in multi-port multi-NUMA deployment scenarios.
> 
> This commit refactors lcore_conf to pointer array and implements
> per-lcore NUMA-aware hugepage allocation, allocating each lcore's
> configuration on its local socket to eliminate remote memory access.
> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>

There is an issue with this change as found by AI:

init_lcore_conf() is called before parse_args(),
so the new lcore_conf allocation happens before --no-numa can set numa_on = 0.
As a result, init_lcore_conf() always uses rte_lcore_to_socket_id()
and allocates each lcore_conf on the lcore's NUMA socket,
even when the user requested non-NUMA allocation.
This can also make startup fail if an enabled lcore is on a socket
without hugepage memory, although --no-numa should force allocations on socket 0.

init_lcore_conf() should be moved after parse_args(), and it should use something like:

  socketid = numa_on ? rte_lcore_to_socket_id(lcore_id) : 0;