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-rw-r--r--nest/route.h25
-rw-r--r--nest/rt-attr.c216
2 files changed, 172 insertions, 69 deletions
diff --git a/nest/route.h b/nest/route.h
index 3f8bf433..531e004b 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -606,8 +606,8 @@ struct rte_src {
typedef struct rta {
- struct rta *next, **pprev; /* Hash chain */
- u32 uc; /* Use count */
+ struct rta * _Atomic next, * _Atomic *pprev; /* Hash chain */
+ _Atomic u32 uc; /* Use count */
u32 hash_key; /* Hash over important fields */
struct ea_list *eattrs; /* Extended Attribute chain */
struct hostentry *hostentry; /* Hostentry for recursive next-hops */
@@ -758,12 +758,6 @@ struct rte_owner {
event *stop;
};
-DEFINE_DOMAIN(attrs);
-extern DOMAIN(attrs) attrs_domain;
-
-#define RTA_LOCK LOCK_DOMAIN(attrs, attrs_domain)
-#define RTA_UNLOCK UNLOCK_DOMAIN(attrs, attrs_domain)
-
#define RTE_SRC_PU_SHIFT 44
#define RTE_SRC_IN_PROGRESS (1ULL << RTE_SRC_PU_SHIFT)
@@ -879,20 +873,23 @@ static inline size_t rta_size(const rta *a) { return sizeof(rta) + sizeof(u32)*a
#define RTA_MAX_SIZE (sizeof(rta) + sizeof(u32)*MPLS_MAX_LABEL_STACK)
rta *rta_lookup(rta *); /* Get rta equivalent to this one, uc++ */
static inline int rta_is_cached(rta *r) { return r->cached; }
+
static inline rta *rta_clone(rta *r) {
- RTA_LOCK;
- r->uc++;
- RTA_UNLOCK;
+ u32 uc = atomic_fetch_add_explicit(&r->uc, 1, memory_order_acq_rel);
+ ASSERT_DIE(uc > 0);
return r;
}
void rta__free(rta *r);
static inline void rta_free(rta *r) {
- RTA_LOCK;
- if (r && !--r->uc)
+ if (!r)
+ return;
+
+ u32 uc = atomic_fetch_sub_explicit(&r->uc, 1, memory_order_acq_rel);
+ if (uc == 1)
rta__free(r);
- RTA_UNLOCK;
}
+
rta *rta_do_cow(rta *o, linpool *lp);
static inline rta * rta_cow(rta *r, linpool *lp) { return rta_is_cached(r) ? rta_do_cow(r, lp) : r; }
static inline void rta_uncache(rta *r) { r->cached = 0; r->uc = 0; }
diff --git a/nest/rt-attr.c b/nest/rt-attr.c
index cb66b65d..9a5498ed 100644
--- a/nest/rt-attr.c
+++ b/nest/rt-attr.c
@@ -54,6 +54,7 @@
#include "lib/hash.h"
#include "lib/idm.h"
#include "lib/resource.h"
+#include "lib/rcu.h"
#include "lib/string.h"
#include <stddef.h>
@@ -85,8 +86,8 @@ const char * rta_dest_names[RTD_MAX] = {
[RTD_PROHIBIT] = "prohibited",
};
-DOMAIN(attrs) attrs_domain;
-DOMAIN(attrs) src_domain;
+DEFINE_DOMAIN(attrs);
+static DOMAIN(attrs) src_domain;
#define SRC_LOCK LOCK_DOMAIN(attrs, src_domain)
#define SRC_UNLOCK UNLOCK_DOMAIN(attrs, src_domain)
@@ -1166,21 +1167,28 @@ ea_append(ea_list *to, ea_list *what)
* rta's
*/
-static uint rta_cache_count;
-static uint rta_cache_size = 32;
-static uint rta_cache_limit;
-static uint rta_cache_mask;
-static rta **rta_hash_table;
+static DOMAIN(attrs) attrs_domain;
-static void
-rta_alloc_hash(void)
+#define RTA_LOCK LOCK_DOMAIN(attrs, attrs_domain)
+#define RTA_UNLOCK UNLOCK_DOMAIN(attrs, attrs_domain)
+
+struct rta_cache {
+ u32 count;
+ u32 size;
+ u32 limit;
+ u32 mask;
+ rta * _Atomic table[0];
+} * _Atomic rta_cache;
+// rta_aux, rta_cache = { .size = ATOMIC_VAR_INIT(32), };
+
+static struct rta_cache *
+rta_alloc_hash(u32 size)
{
- rta_hash_table = mb_allocz(rta_pool, sizeof(rta *) * rta_cache_size);
- if (rta_cache_size < 32768)
- rta_cache_limit = rta_cache_size * 2;
- else
- rta_cache_limit = ~0;
- rta_cache_mask = rta_cache_size - 1;
+ struct rta_cache *c = mb_allocz(rta_pool, sizeof(struct rta_cache) + sizeof(rta * _Atomic) * size);
+ c->size = size;
+ c->limit = (size >> 20) ? (~0U) : (size * 2);
+ c->mask = size - 1;
+ return c;
}
static inline uint
@@ -1234,34 +1242,88 @@ rta_copy(rta *o)
}
static inline void
-rta_insert(rta *r)
+rta_insert(rta *r, struct rta_cache *c)
{
- uint h = r->hash_key & rta_cache_mask;
- r->next = rta_hash_table[h];
- if (r->next)
- r->next->pprev = &r->next;
- r->pprev = &rta_hash_table[h];
- rta_hash_table[h] = r;
+ uint h = r->hash_key & c->mask;
+ rta *next = atomic_load_explicit(&c->table[h], memory_order_relaxed);
+
+ atomic_store_explicit(&r->next, next, memory_order_relaxed);
+ r->pprev = &c->table[h];
+
+ if (next)
+ next->pprev = &r->next;
+
+ /* This store MUST be the last and MUST have release order for thread-safety */
+ atomic_store_explicit(&c->table[h], r, memory_order_release);
}
static void
-rta_rehash(void)
+rta_rehash(struct rta_cache *c)
{
- uint ohs = rta_cache_size;
- uint h;
- rta *r, *n;
- rta **oht = rta_hash_table;
-
- rta_cache_size = 2*rta_cache_size;
- DBG("Rehashing rta cache from %d to %d entries.\n", ohs, rta_cache_size);
- rta_alloc_hash();
- for(h=0; h<ohs; h++)
- for(r=oht[h]; r; r=n)
+ u32 os = c->size;
+
+ struct rta_cache *nc = rta_alloc_hash(os * 2);
+ nc->count = c->count;
+
+ /* First we simply copy every chain to both new locations */
+ for (u32 h = 0; h < os; h++)
+ {
+ rta *r = atomic_load_explicit(&c->table[h], memory_order_relaxed);
+ atomic_store_explicit(&nc->table[h], r, memory_order_relaxed);
+ atomic_store_explicit(&nc->table[h + os], r, memory_order_relaxed);
+ }
+
+ /* Then we exchange the hashes; release semantics forces the previous code to be already done */
+ atomic_store_explicit(&rta_cache, nc, memory_order_release);
+
+ /* And now we pass through both chains and filter them */
+ for (u32 h = 0; h < c->size; h++)
+ {
+ rta * _Atomic * ap = &nc->table[h];
+ rta * _Atomic * bp = &nc->table[h + os];
+
+ rta *r = atomic_load_explicit(ap, memory_order_relaxed);
+ ASSERT_DIE(r == atomic_load_explicit(bp, memory_order_relaxed));
+
+ while (r)
+ {
+ if (r->hash_key & os)
+ {
+ r->pprev = bp;
+ atomic_store_explicit(bp, r, memory_order_release);
+ bp = &r->next;
+ }
+ else
{
- n = r->next;
- rta_insert(r);
+ r->pprev = ap;
+ atomic_store_explicit(ap, r, memory_order_release);
+ ap = &r->next;
}
- mb_free(oht);
+
+ r = atomic_load_explicit(&r->next, memory_order_acquire);
+ }
+
+ atomic_store_explicit(ap, NULL, memory_order_release);
+ atomic_store_explicit(bp, NULL, memory_order_release);
+ }
+
+ synchronize_rcu();
+ mb_free(c);
+}
+
+static rta *
+rta_find(rta *o, u32 h, struct rta_cache *c)
+{
+ rta *r = NULL;
+
+ for (r = atomic_load_explicit(&c->table[h & c->mask], memory_order_acquire); r; r = atomic_load_explicit(&r->next, memory_order_acquire))
+ if (r->hash_key == h && rta_same(r, o))
+ {
+ atomic_fetch_add_explicit(&r->uc, 1, memory_order_acq_rel);
+ return r;
+ }
+
+ return NULL;
}
/**
@@ -1289,24 +1351,34 @@ rta_lookup(rta *o)
h = rta_hash(o);
+ /* Lockless lookup */
+ rcu_read_lock();
+ r = rta_find(o, h, atomic_load_explicit(&rta_cache, memory_order_acquire));
+ rcu_read_unlock();
+
+ if (r)
+ return r;
+
RTA_LOCK;
- for(r=rta_hash_table[h & rta_cache_mask]; r; r=r->next)
- if (r->hash_key == h && rta_same(r, o))
- {
- r->uc++;
- RTA_UNLOCK;
- return r;
- }
+ /* Locked lookup to avoid duplicates if possible */
+ struct rta_cache *c = atomic_load_explicit(&rta_cache, memory_order_acquire);
+ r = rta_find(o, h, c);
+ if (r)
+ {
+ RTA_UNLOCK;
+ return r;
+ }
+ /* Store the rta */
r = rta_copy(o);
r->hash_key = h;
r->cached = 1;
rt_lock_hostentry(r->hostentry);
- rta_insert(r);
+ rta_insert(r, c);
- if (++rta_cache_count > rta_cache_limit)
- rta_rehash();
+ if (++c->count > c->limit)
+ rta_rehash(c);
RTA_UNLOCK;
return r;
@@ -1315,17 +1387,47 @@ rta_lookup(rta *o)
void
rta__free(rta *a)
{
- ASSERT(rta_cache_count && a->cached);
- rta_cache_count--;
- *a->pprev = a->next;
- if (a->next)
- a->next->pprev = a->pprev;
+ ASSERT(a->cached);
+
+ RTA_LOCK;
+ struct rta_cache *c = atomic_load_explicit(&rta_cache, memory_order_acquire);
+
+ if (atomic_load_explicit(&a->uc, memory_order_acquire))
+ {
+ /* Acquired inbetween */
+ RTA_UNLOCK;
+ return;
+ }
+
+ /* Relink the forward pointer */
+ rta *next = atomic_load_explicit(&a->next, memory_order_acquire);
+ atomic_store_explicit(a->pprev, next, memory_order_release);
+
+ /* Relink the backwards pointer */
+ if (next)
+ next->pprev = a->pprev;
+
+ /* Wait until nobody knows about us */
+ synchronize_rcu();
+
+ if (atomic_load_explicit(&a->uc, memory_order_acquire))
+ {
+ /* Acquired inbetween, relink back */
+ rta_insert(a, c);
+ RTA_UNLOCK;
+ return;
+ }
+
+ /* Cleared to free the memory */
rt_unlock_hostentry(a->hostentry);
if (a->nh.next)
nexthop_free(a->nh.next);
ea_free(a->eattrs);
a->cached = 0;
+ c->count--;
sl_free(rta_slab(a), a);
+
+ RTA_UNLOCK;
}
rta *
@@ -1394,9 +1496,13 @@ rta_dump_all(void)
RTA_LOCK;
- debug("Route attribute cache (%d entries, rehash at %d):\n", rta_cache_count, rta_cache_limit);
- for(h=0; h<rta_cache_size; h++)
- for(a=rta_hash_table[h]; a; a=a->next)
+ struct rta_cache *c = atomic_load_explicit(&rta_cache, memory_order_acquire);
+
+ debug("Route attribute cache (%d entries, rehash at %d):\n", c->count, c->limit);
+ for(h=0; h<c->size; h++)
+ for(a = atomic_load_explicit(&c->table[h], memory_order_acquire);
+ a;
+ a = atomic_load_explicit(&a->next, memory_order_acquire))
{
debug("%p ", a);
rta_dump(a);
@@ -1440,7 +1546,7 @@ rta_init(void)
nexthop_slab_[2] = sl_new(rta_pool, sizeof(struct nexthop) + sizeof(u32)*2);
nexthop_slab_[3] = sl_new(rta_pool, sizeof(struct nexthop) + sizeof(u32)*MPLS_MAX_LABEL_STACK);
- rta_alloc_hash();
+ atomic_store_explicit(&rta_cache, rta_alloc_hash(32), memory_order_relaxed);
rte_src_init();
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-18 02:33:31 +0000