These makes cmap_find 10% faster on GCC 4.7 (-O2 -g).
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
lib/cmap.c | 44 +++++++++++++++++++++++++++-----------------
1 file changed, 27 insertions(+), 17 deletions(-)
diff --git a/lib/cmap.c b/lib/cmap.c
index ba744cc..fa7c0bb 100644
--- a/lib/cmap.c
+++ b/lib/cmap.c
@@ -304,35 +304,45 @@ cmap_find(const struct cmap *cmap, uint32_t hash)
struct cmap_bucket *b2;
uint32_t c1, c2;
int i;
+ struct cmap_node *node;
-retry:
b1 = &impl->buckets[h1 & impl->mask];
+ b2 = &impl->buckets[h2 & impl->mask];
+retry:
+ node = NULL;
c1 = read_even_counter(b1);
for (i = 0; i < CMAP_K; i++) {
- struct cmap_node *node = cmap_node_next(&b1->nodes[i]);
-
- if (node && cmap_get_hash(&b1->hashes[i]) == hash) {
- if (counter_changed(b1, c1)) {
- goto retry;
- }
- return node;
+ if (cmap_get_hash(&b1->hashes[i]) == hash) {
+ node = cmap_node_next(&b1->nodes[i]);
+ break;
}
}
+ if (OVS_UNLIKELY(counter_changed(b1, c1))) {
+ goto retry;
+ }
+ if (node) {
+ return node;
+ }
- b2 = &impl->buckets[h2 & impl->mask];
+retry2:
+ node = NULL;
c2 = read_even_counter(b2);
for (i = 0; i < CMAP_K; i++) {
- struct cmap_node *node = cmap_node_next(&b2->nodes[i]);
-
- if (node && cmap_get_hash(&b2->hashes[i]) == hash) {
- if (counter_changed(b2, c2)) {
- goto retry;
- }
- return node;
+ if (cmap_get_hash(&b2->hashes[i]) == hash) {
+ node = cmap_node_next(&b2->nodes[i]);
+ break;
}
}
+ if (OVS_UNLIKELY(counter_changed(b2, c2))) {
+ goto retry2;
+ }
+ if (node) {
+ return node;
+ }
- if (counter_changed(b1, c1) || counter_changed(b2, c2)) {
+ /* We just got a stable reading on 'b2', but a node could have been moved
+ * to 'b1', so we need to chack the 'c1' again. */
+ if (counter_changed(b1, c1)) {
goto retry;
}
return NULL;
--
1.7.10.4
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