Olivier (maintainer of the Ring),
I would like to suggest a couple of minor optimizations to the ring library.
1. Testing if the ring is empty is as simple as comparing the producer and
consumer pointers:
static inline int
rte_ring_empty(const struct rte_ring *r)
{
- return rte_ring_count(r) == 0;
+ uint32_t prod_tail = r->prod.tail;
+ uint32_t cons_tail = r->cons.tail;
+ return cons_tail == prod_tail;
}
In theory, this optimization reduces the number of potential cache misses from
3 to 2 by not having to read r->mask in rte_ring_count().
2. It is not possible to enqueue more elements than the capacity of a ring, so
the count function does not need to test if the capacity is exceeded:
static inline unsigned
rte_ring_count(const struct rte_ring *r)
{
uint32_t prod_tail = r->prod.tail;
uint32_t cons_tail = r->cons.tail;
uint32_t count = (prod_tail - cons_tail) & r->mask;
- return (count > r->capacity) ? r->capacity : count;
+ return count;
}
I cannot even come up with a race condition in this function where the count
would exceed the capacity. Maybe I missed something?
Med venlig hilsen / kind regards
- Morten Brørup
