> From: Konstantin Ananyev [mailto:[email protected]] > Sent: Thursday, 30 April 2026 19.22 > > Hi Morten, > > > 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. > > I don't see any harm with it, and in theory it might help in some > cases... > Though I wonder how real is that problem? > Did you ever observe such contention to happen?
I never observed a problem with this. The risk of contention depends on what is allocated in the memory after the ring. Which is application specific. It seems like a purely theoretical issue, but should be fixed anyway, to eliminate that risk. > > > Signed-off-by: Morten Brørup <[email protected]> > > --- > > lib/ring/rte_ring.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/lib/ring/rte_ring.c b/lib/ring/rte_ring.c > > index f10050a1c4..9ccc62cd42 100644 > > --- a/lib/ring/rte_ring.c > > +++ b/lib/ring/rte_ring.c > > @@ -73,8 +73,11 @@ 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; > > sz = RTE_ALIGN(sz, RTE_CACHE_LINE_SIZE); > > + sz += RTE_CACHE_GUARD_LINES * RTE_CACHE_LINE_SIZE; > > return sz; > > } > > > > -- > > 2.43.0
