Acked-by: Chengwen Feng <[email protected]>
On 5/6/2026 12:13 AM, Morten Brørup wrote:
> Added cache guard after the table holding the ring elements, to avoid
> false sharing conflicts caused by next-line hardware prefetchers when
> accessing elements at the end of the ring table.
>
> Signed-off-by: Morten Brørup <[email protected]>
> Acked-by: Konstantin Ananyev <[email protected]>
> ---
> v2:
> * Added comment describing reason for padding. (Konstantin)
> ---
> lib/ring/rte_ring.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/lib/ring/rte_ring.c b/lib/ring/rte_ring.c
> index f10050a1c4..10b52dc679 100644
> --- a/lib/ring/rte_ring.c
> +++ b/lib/ring/rte_ring.c
> @@ -73,8 +73,15 @@ rte_ring_get_memsize_elem(unsigned int esize, unsigned int
> count)
> return -EINVAL;
> }
>
> + static_assert(sizeof(struct rte_ring) ==
> RTE_CACHE_LINE_ROUNDUP(sizeof(struct rte_ring)),
> + "Size of struct rte_ring not cache line aligned");
> sz = sizeof(struct rte_ring) + (ssize_t)count * esize;
> + /* Add padding, to guard against false sharing-like effects
> + * on systems with a next-N-lines hardware prefetcher, when
> + * accessing elements at the end of the ring table.
> + */
> sz = RTE_ALIGN(sz, RTE_CACHE_LINE_SIZE);
> + sz += RTE_CACHE_GUARD_LINES * RTE_CACHE_LINE_SIZE;
> return sz;
> }
>
