rds: Use RCU for the bind lookup searches
The RDS bind lookups are somewhat expensive in terms of CPU
time and locking overhead. This commit changes them into a
faster RCU based hash tree instead of the rbtrees they were using
before.
On large NUMA systems it is a significant improvement.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/net/rds/bind.c b/net/rds/bind.c
index a65afff..2f6b3fc 100644
--- a/net/rds/bind.c
+++ b/net/rds/bind.c
@@ -34,45 +34,52 @@
#include <net/sock.h>
#include <linux/in.h>
#include <linux/if_arp.h>
+#include <linux/jhash.h>
#include "rds.h"
-/*
- * XXX this probably still needs more work.. no INADDR_ANY, and rbtrees aren't
- * particularly zippy.
- *
- * This is now called for every incoming frame so we arguably care much more
- * about it than we used to.
- */
-static DEFINE_RWLOCK(rds_bind_lock);
-static struct rb_root rds_bind_tree = RB_ROOT;
+#define BIND_HASH_SIZE 1024
+static struct hlist_head bind_hash_table[BIND_HASH_SIZE];
+static DEFINE_SPINLOCK(rds_bind_lock);
-static struct rds_sock *rds_bind_tree_walk(__be32 addr, __be16 port,
- struct rds_sock *insert)
+static struct hlist_head *hash_to_bucket(__be32 addr, __be16 port)
{
- struct rb_node **p = &rds_bind_tree.rb_node;
- struct rb_node *parent = NULL;
+ return bind_hash_table + (jhash_2words((u32)addr, (u32)port, 0) &
+ (BIND_HASH_SIZE - 1));
+}
+
+static struct rds_sock *rds_bind_lookup(__be32 addr, __be16 port,
+ struct rds_sock *insert)
+{
struct rds_sock *rs;
+ struct hlist_node *node;
+ struct hlist_head *head = hash_to_bucket(addr, port);
u64 cmp;
u64 needle = ((u64)be32_to_cpu(addr) << 32) | be16_to_cpu(port);
- while (*p) {
- parent = *p;
- rs = rb_entry(parent, struct rds_sock, rs_bound_node);
-
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(rs, node, head, rs_bound_node) {
cmp = ((u64)be32_to_cpu(rs->rs_bound_addr) << 32) |
be16_to_cpu(rs->rs_bound_port);
- if (needle < cmp)
- p = &(*p)->rb_left;
- else if (needle > cmp)
- p = &(*p)->rb_right;
- else
+ if (cmp == needle) {
+ rcu_read_unlock();
return rs;
+ }
}
+ rcu_read_unlock();
if (insert) {
- rb_link_node(&insert->rs_bound_node, parent, p);
- rb_insert_color(&insert->rs_bound_node, &rds_bind_tree);
+ /*
+ * make sure our addr and port are set before
+ * we are added to the list, other people
+ * in rcu will find us as soon as the
+ * hlist_add_head_rcu is done
+ */
+ insert->rs_bound_addr = addr;
+ insert->rs_bound_port = port;
+ rds_sock_addref(insert);
+
+ hlist_add_head_rcu(&insert->rs_bound_node, head);
}
return NULL;
}
@@ -86,15 +93,13 @@
struct rds_sock *rds_find_bound(__be32 addr, __be16 port)
{
struct rds_sock *rs;
- unsigned long flags;
- read_lock_irqsave(&rds_bind_lock, flags);
- rs = rds_bind_tree_walk(addr, port, NULL);
+ rs = rds_bind_lookup(addr, port, NULL);
+
if (rs && !sock_flag(rds_rs_to_sk(rs), SOCK_DEAD))
rds_sock_addref(rs);
else
rs = NULL;
- read_unlock_irqrestore(&rds_bind_lock, flags);
rdsdebug("returning rs %p for %pI4:%u\n", rs, &addr,
ntohs(port));
@@ -116,28 +121,21 @@
last = rover - 1;
}
- write_lock_irqsave(&rds_bind_lock, flags);
+ spin_lock_irqsave(&rds_bind_lock, flags);
do {
if (rover == 0)
rover++;
- if (!rds_bind_tree_walk(addr, cpu_to_be16(rover), rs)) {
- *port = cpu_to_be16(rover);
+ if (!rds_bind_lookup(addr, cpu_to_be16(rover), rs)) {
+ *port = rs->rs_bound_port;
ret = 0;
+ rdsdebug("rs %p binding to %pI4:%d\n",
+ rs, &addr, (int)ntohs(*port));
break;
}
} while (rover++ != last);
- if (ret == 0) {
- rs->rs_bound_addr = addr;
- rs->rs_bound_port = *port;
- rds_sock_addref(rs);
-
- rdsdebug("rs %p binding to %pI4:%d\n",
- rs, &addr, (int)ntohs(*port));
- }
-
- write_unlock_irqrestore(&rds_bind_lock, flags);
+ spin_unlock_irqrestore(&rds_bind_lock, flags);
return ret;
}
@@ -146,19 +144,19 @@
{
unsigned long flags;
- write_lock_irqsave(&rds_bind_lock, flags);
+ spin_lock_irqsave(&rds_bind_lock, flags);
if (rs->rs_bound_addr) {
rdsdebug("rs %p unbinding from %pI4:%d\n",
rs, &rs->rs_bound_addr,
ntohs(rs->rs_bound_port));
- rb_erase(&rs->rs_bound_node, &rds_bind_tree);
+ hlist_del_init_rcu(&rs->rs_bound_node);
rds_sock_put(rs);
rs->rs_bound_addr = 0;
}
- write_unlock_irqrestore(&rds_bind_lock, flags);
+ spin_unlock_irqrestore(&rds_bind_lock, flags);
}
int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
@@ -198,5 +196,9 @@
out:
release_sock(sk);
+
+ /* we might have called rds_remove_bound on error */
+ if (ret)
+ synchronize_rcu();
return ret;
}