Atomic operations are relatively expensive because they involve implicit
memory synchronizations and pipeline flushes. During packet_init()
processing we know that there are no other references to this packet,
so avoid this overhead via a controlled breach of the atomic type to
set the initial reference count directly.
Signed-off-by: Bill Fischofer <bill.fischo...@linaro.org>
---
platform/linux-generic/include/odp_packet_internal.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/platform/linux-generic/include/odp_packet_internal.h
b/platform/linux-generic/include/odp_packet_internal.h
index 2db042e0..593f30dd 100644
--- a/platform/linux-generic/include/odp_packet_internal.h
+++ b/platform/linux-generic/include/odp_packet_internal.h
@@ -262,7 +262,12 @@ static inline uint32_t packet_ref_count(odp_packet_hdr_t
*pkt_hdr)
static inline void packet_ref_count_set(odp_packet_hdr_t *pkt_hdr, uint32_t n)
{
- odp_atomic_init_u32(&pkt_hdr->ref_count, n);
+ /* Only used during init when there are no other possible
+ * references to this pkt, so avoid the "atomic" overhead by
+ * a controlled breach of the atomic type here. This saves
+ * over 10% of the pathlength in routines like packet_alloc().
+ */
+ pkt_hdr->ref_count.v = n;
}
static inline void packet_set_len(odp_packet_hdr_t *pkt_hdr, uint32_t len)
--
2.12.0.rc1
