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authorDave Barach <dbarach@cisco.com>2017-07-21 10:44:27 -0400
committerJohn Lo <loj@cisco.com>2017-07-23 00:55:13 +0000
commit858c06fac65e7ad05dc6e739a51e8d87a544e0fe (patch)
tree9ec733957457854b84a8ae1aa37aa47cf5d641c2
parent6534b7aa13bc5bed15ed87f47bb766405963e9e8 (diff)
Atomic bucket lock
Change-Id: I84908b9ad30d7555024e98b69ed37b111f31c27a Signed-off-by: Dave Barach <dbarach@cisco.com>
-rw-r--r--src/vppinfra/bihash_template.c27
-rw-r--r--src/vppinfra/bihash_template.h72
2 files changed, 58 insertions, 41 deletions
diff --git a/src/vppinfra/bihash_template.c b/src/vppinfra/bihash_template.c
index e3a5759d766..b5eb379a0f5 100644
--- a/src/vppinfra/bihash_template.c
+++ b/src/vppinfra/bihash_template.c
@@ -135,8 +135,9 @@ BV (make_working_copy) (BVT (clib_bihash) * h, BVT (clib_bihash_bucket) * b)
clib_mem_set_heap (oldheap);
- /* Turn off the cache */
- BV (clib_bihash_cache_enable_disable) (b, 0);
+ /* Lock the bucket... */
+ while (BV (clib_bihash_lock_bucket) (b) == 0)
+ ;
v = BV (clib_bihash_get_value) (h, b->offset);
@@ -416,7 +417,7 @@ expand_ok:
unlock:
BV (clib_bihash_reset_cache) (b);
- BV (clib_bihash_cache_enable_disable) (b, 1 /* enable */ );
+ BV (clib_bihash_unlock_bucket) (b);
CLIB_MEMORY_BARRIER ();
h->writer_lock[0] = 0;
return rv;
@@ -444,7 +445,7 @@ int BV (clib_bihash_search)
return -1;
/* Check the cache, if currently enabled */
- if (PREDICT_TRUE (b->cache_lru & (1 << 15)))
+ if (PREDICT_TRUE ((b->cache_lru & (1 << 15)) == 0))
{
limit = BIHASH_KVP_CACHE_SIZE;
kvp = b->cache;
@@ -475,16 +476,16 @@ int BV (clib_bihash_search)
*valuep = v->kvp[i];
/* Shut off the cache */
- BV (clib_bihash_cache_enable_disable) (b, 0);
- CLIB_MEMORY_BARRIER ();
-
- cache_slot = BV (clib_bihash_get_lru) (b);
- b->cache[cache_slot] = v->kvp[i];
- BV (clib_bihash_update_lru) (b, cache_slot);
+ if (BV (clib_bihash_lock_bucket) (b))
+ {
+ cache_slot = BV (clib_bihash_get_lru) (b);
+ b->cache[cache_slot] = v->kvp[i];
+ BV (clib_bihash_update_lru) (b, cache_slot);
- /* Reenable the cache */
- BV (clib_bihash_cache_enable_disable) (b, 1);
- h->cache_misses++;
+ /* Reenable the cache */
+ BV (clib_bihash_unlock_bucket) (b);
+ h->cache_misses++;
+ }
return 0;
}
}
diff --git a/src/vppinfra/bihash_template.h b/src/vppinfra/bihash_template.h
index feb6fb68797..3d9c59cb933 100644
--- a/src/vppinfra/bihash_template.h
+++ b/src/vppinfra/bihash_template.h
@@ -182,13 +182,29 @@ static inline void BV (clib_bihash_reset_cache) (BVT (clib_bihash_bucket) * b)
b->cache_lru = initial_lru_value;
}
-static inline void BV (clib_bihash_cache_enable_disable)
- (BVT (clib_bihash_bucket) * b, u8 enable)
+static inline int BV (clib_bihash_lock_bucket) (BVT (clib_bihash_bucket) * b)
{
BVT (clib_bihash_bucket) tmp_b;
+ u64 rv;
+
+ tmp_b.as_u64 = 0;
+ tmp_b.cache_lru = 1 << 15;
+
+ rv = __sync_fetch_and_or (&b->as_u64, tmp_b.as_u64);
+ tmp_b.as_u64 = rv;
+ /* Was already locked? */
+ if (tmp_b.cache_lru & (1 << 15))
+ return 0;
+ return 1;
+}
+
+static inline void BV (clib_bihash_unlock_bucket)
+ (BVT (clib_bihash_bucket) * b)
+{
+ BVT (clib_bihash_bucket) tmp_b;
+
tmp_b.as_u64 = b->as_u64;
- tmp_b.cache_lru &= 0x7FFF;
- tmp_b.cache_lru |= enable << 15;
+ tmp_b.cache_lru &= ~(1 << 15);
b->as_u64 = tmp_b.as_u64;
}
@@ -249,8 +265,8 @@ static inline int BV (clib_bihash_search_inline)
if (b->offset == 0)
return -1;
- /* Check the cache, if currently enabled */
- if (PREDICT_TRUE (b->cache_lru & (1 << 15)))
+ /* Check the cache, if not currently locked */
+ if (PREDICT_TRUE ((b->cache_lru & (1 << 15)) == 0))
{
limit = BIHASH_KVP_CACHE_SIZE;
kvp = b->cache;
@@ -282,17 +298,17 @@ static inline int BV (clib_bihash_search_inline)
u8 cache_slot;
*key_result = v->kvp[i];
- /* Shut off the cache */
- BV (clib_bihash_cache_enable_disable) (b, 0);
- CLIB_MEMORY_BARRIER ();
-
- cache_slot = BV (clib_bihash_get_lru) (b);
- b->cache[cache_slot] = v->kvp[i];
- BV (clib_bihash_update_lru) (b, cache_slot);
+ /* Try to lock the bucket */
+ if (BV (clib_bihash_lock_bucket) (b))
+ {
+ cache_slot = BV (clib_bihash_get_lru) (b);
+ b->cache[cache_slot] = v->kvp[i];
+ BV (clib_bihash_update_lru) (b, cache_slot);
- /* Reenable the cache */
- BV (clib_bihash_cache_enable_disable) (b, 1);
- h->cache_misses++;
+ /* Unlock the bucket */
+ BV (clib_bihash_unlock_bucket) (b);
+ h->cache_misses++;
+ }
return 0;
}
}
@@ -320,8 +336,8 @@ static inline int BV (clib_bihash_search_inline_2)
if (b->offset == 0)
return -1;
- /* Check the cache, if currently enabled */
- if (PREDICT_TRUE (b->cache_lru & (1 << 15)))
+ /* Check the cache, if currently unlocked */
+ if (PREDICT_TRUE ((b->cache_lru & (1 << 15)) == 0))
{
limit = BIHASH_KVP_CACHE_SIZE;
kvp = b->cache;
@@ -352,17 +368,17 @@ static inline int BV (clib_bihash_search_inline_2)
u8 cache_slot;
*valuep = v->kvp[i];
- /* Shut off the cache */
- BV (clib_bihash_cache_enable_disable) (b, 0);
- CLIB_MEMORY_BARRIER ();
-
- cache_slot = BV (clib_bihash_get_lru) (b);
- b->cache[cache_slot] = v->kvp[i];
- BV (clib_bihash_update_lru) (b, cache_slot);
+ /* Try to lock the bucket */
+ if (BV (clib_bihash_lock_bucket) (b))
+ {
+ cache_slot = BV (clib_bihash_get_lru) (b);
+ b->cache[cache_slot] = v->kvp[i];
+ BV (clib_bihash_update_lru) (b, cache_slot);
- /* Reenable the cache */
- BV (clib_bihash_cache_enable_disable) (b, 1);
- h->cache_misses++;
+ /* Reenable the cache */
+ BV (clib_bihash_unlock_bucket) (b);
+ h->cache_misses++;
+ }
return 0;
}
}