diff mbox

[API-NEXT] linux-generic: packet: minimize use of atomic ops on free paths

Message ID 20170216201538.23131-1-bill.fischofer@linaro.org
State Superseded
Headers show

Commit Message

Bill Fischofer Feb. 16, 2017, 8:15 p.m. UTC 
While reference counts are implemented as atomics, try to avoid
unnecessary atomic decrement operations in free paths. This streamlines
free processing in the expected case where packets do not contain
shared segments.

Signed-off-by: Bill Fischofer <bill.fischofer@linaro.org>

---
 platform/linux-generic/odp_packet.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

-- 
2.12.0.rc1
diff mbox

Patch

diff --git a/platform/linux-generic/odp_packet.c b/platform/linux-generic/odp_packet.c
index 4d2cde12..0019fae9 100644
--- a/platform/linux-generic/odp_packet.c
+++ b/platform/linux-generic/odp_packet.c
@@ -477,8 +477,10 @@  static inline void free_bufs(odp_packet_hdr_t *pkt_hdr, int first, int num)
 	for (i = 0, nfree = 0; i < num; i++) {
 		odp_packet_hdr_t *hdr = pkt_hdr->buf_hdr.seg[first + i].hdr;
 
-		if (packet_ref_dec(hdr) == 1)
+		if (packet_ref_count(hdr) == 1)
 			buf[nfree++] = buffer_handle(hdr);
+		else
+			packet_ref_dec(hdr);
 	}
 
 	if (nfree > 0)
@@ -499,8 +501,10 @@  static inline odp_packet_hdr_t *free_segments(odp_packet_hdr_t *pkt_hdr,
 		for (i = 0, nfree = 0; i < num; i++) {
 			new_hdr = pkt_hdr->buf_hdr.seg[i].hdr;
 
-			if (packet_ref_dec(new_hdr) == 1)
+			if (packet_ref_count(new_hdr) == 1)
 				buf[nfree++] = buffer_handle(new_hdr);
+			else
+				packet_ref_dec(new_hdr);
 		}
 
 		/* First remaining segment is the new packet descriptor */
@@ -643,12 +647,12 @@  static inline odp_packet_hdr_t *packet_free_to_list(odp_packet_hdr_t *pkt_hdr,
 	int num_seg, i;
 
 	do {
-		ref_count = packet_ref_count(pkt_hdr) - 1;
+		ref_count = packet_ref_count(pkt_hdr);
 		num_seg = pkt_hdr->buf_hdr.segcount;
 		ref_hdr = pkt_hdr->ref_hdr;
 
 		if (odp_likely((CONFIG_PACKET_MAX_SEGS == 1 || num_seg == 1) &&
-			       ref_count == 0)) {
+			       ref_count == 1)) {
 			if (*nfree >= nbufs)
 				break;
 
@@ -661,11 +665,13 @@  static inline odp_packet_hdr_t *packet_free_to_list(odp_packet_hdr_t *pkt_hdr,
 				odp_packet_hdr_t *hdr =
 					pkt_hdr->buf_hdr.seg[i].hdr;
 
-				if (packet_ref_dec(hdr) == 1)
+				if (packet_ref_count(hdr) == 1)
 					buf[(*nfree)++] = buffer_handle(hdr);
+				else
+					packet_ref_dec(hdr);
 			}
 
-			if (ref_count == 1)
+			if (ref_count == 2)
 				pkt_hdr->unshared_len = pkt_hdr->frame_len;
 		}
 
@@ -682,18 +688,18 @@  static inline void packet_free(odp_packet_hdr_t *pkt_hdr)
 	int num_seg;
 
 	do {
-		ref_count = packet_ref_count(pkt_hdr) - 1;
+		ref_count = packet_ref_count(pkt_hdr);
 		num_seg = pkt_hdr->buf_hdr.segcount;
 		ref_hdr = pkt_hdr->ref_hdr;
 
 		if (odp_likely((CONFIG_PACKET_MAX_SEGS == 1 || num_seg == 1) &&
-			       ref_count == 0)) {
+			       ref_count == 1)) {
 			buffer_free_multi((odp_buffer_t *)
 					  &pkt_hdr->buf_hdr.handle.handle, 1);
 		} else {
 			free_bufs(pkt_hdr, 0, num_seg);
 
-			if (ref_count == 1)
+			if (ref_count == 2)
 				pkt_hdr->unshared_len = pkt_hdr->frame_len;
 		}