[dpdk-dev] [PATCH 2/2] ring: empty optimization
Morten Brørup
mb at smartsharesystems.com
Tue May 19 17:27:25 CEST 2020
Testing if the ring is empty is as simple as comparing the producer and
consumer pointers.
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().
The modification of this function were also discussed in the RFC here:
https://mails.dpdk.org/archives/dev/2020-April/165752.html
Signed-off-by: Morten Brørup <mb at smartsharesystems.com>
---
lib/librte_ring/rte_ring.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index 9078e7c24..f67141482 100644
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -733,7 +733,9 @@ rte_ring_full(const struct rte_ring *r)
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;
}
/**
--
2.17.1
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