rds: reduce memory footprint for RDS when transport is RDMA

RDS over IB does not use multipath RDS, so the array
of additional rds_conn_path structures is always superfluous
in this case. Reduce the memory footprint of the rds module
by making this a dynamic allocation predicated on whether
the transport is mp_capable.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Tested-by: Efrain Galaviz <efrain.galaviz@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/rds/connection.c b/net/rds/connection.c
index 005bca6..7ee2d5d 100644 (file)
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -151,6 +151,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
        struct rds_transport *loop_trans;
        unsigned long flags;
        int ret, i;
+       int npaths = (trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);
 
        rcu_read_lock();
        conn = rds_conn_lookup(net, head, laddr, faddr, trans);
@@ -172,6 +173,12 @@ static struct rds_connection *__rds_conn_create(struct net *net,
                conn = ERR_PTR(-ENOMEM);
                goto out;
        }
+       conn->c_path = kcalloc(npaths, sizeof(struct rds_conn_path), gfp);
+       if (!conn->c_path) {
+               kmem_cache_free(rds_conn_slab, conn);
+               conn = ERR_PTR(-ENOMEM);
+               goto out;
+       }
 
        INIT_HLIST_NODE(&conn->c_hash_node);
        conn->c_laddr = laddr;
@@ -181,6 +188,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 
        ret = rds_cong_get_maps(conn);
        if (ret) {
+               kfree(conn->c_path);
                kmem_cache_free(rds_conn_slab, conn);
                conn = ERR_PTR(ret);
                goto out;
@@ -207,13 +215,14 @@ static struct rds_connection *__rds_conn_create(struct net *net,
        conn->c_trans = trans;
 
        init_waitqueue_head(&conn->c_hs_waitq);
-       for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+       for (i = 0; i < npaths; i++) {
                __rds_conn_path_init(conn, &conn->c_path[i],
                                     is_outgoing);
                conn->c_path[i].cp_index = i;
        }
        ret = trans->conn_alloc(conn, gfp);
        if (ret) {
+               kfree(conn->c_path);
                kmem_cache_free(rds_conn_slab, conn);
                conn = ERR_PTR(ret);
                goto out;
@@ -236,6 +245,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
                /* Creating passive conn */
                if (parent->c_passive) {
                        trans->conn_free(conn->c_path[0].cp_transport_data);
+                       kfree(conn->c_path);
                        kmem_cache_free(rds_conn_slab, conn);
                        conn = parent->c_passive;
                } else {
@@ -252,7 +262,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
                        struct rds_conn_path *cp;
                        int i;
 
-                       for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+                       for (i = 0; i < npaths; i++) {
                                cp = &conn->c_path[i];
                                /* The ->conn_alloc invocation may have
                                 * allocated resource for all paths, so all
@@ -261,6 +271,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
                                if (cp->cp_transport_data)
                                        trans->conn_free(cp->cp_transport_data);
                        }
+                       kfree(conn->c_path);
                        kmem_cache_free(rds_conn_slab, conn);
                        conn = found;
                } else {
@@ -407,6 +418,7 @@ void rds_conn_destroy(struct rds_connection *conn)
        unsigned long flags;
        int i;
        struct rds_conn_path *cp;
+       int npaths = (conn->c_trans->t_mp_capable ? RDS_MPATH_WORKERS : 1);
 
        rdsdebug("freeing conn %p for %pI4 -> "
                 "%pI4\n", conn, &conn->c_laddr,
@@ -420,7 +432,7 @@ void rds_conn_destroy(struct rds_connection *conn)
        synchronize_rcu();
 
        /* shut the connection down */
-       for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+       for (i = 0; i < npaths; i++) {
                cp = &conn->c_path[i];
                rds_conn_path_destroy(cp);
                BUG_ON(!list_empty(&cp->cp_retrans));
@@ -434,6 +446,7 @@ void rds_conn_destroy(struct rds_connection *conn)
        rds_cong_remove_conn(conn);
 
        put_net(conn->c_net);
+       kfree(conn->c_path);
        kmem_cache_free(rds_conn_slab, conn);
 
        spin_lock_irqsave(&rds_conn_lock, flags);
@@ -464,8 +477,12 @@ static void rds_conn_message_info(struct socket *sock, unsigned int len,
             i++, head++) {
                hlist_for_each_entry_rcu(conn, head, c_hash_node) {
                        struct rds_conn_path *cp;
+                       int npaths;
+
+                       npaths = (conn->c_trans->t_mp_capable ?
+                                RDS_MPATH_WORKERS : 1);
 
-                       for (j = 0; j < RDS_MPATH_WORKERS; j++) {
+                       for (j = 0; j < npaths; j++) {
                                cp = &conn->c_path[j];
                                if (want_send)
                                        list = &cp->cp_send_queue;
@@ -486,8 +503,6 @@ static void rds_conn_message_info(struct socket *sock, unsigned int len,
                                }
 
                                spin_unlock_irqrestore(&cp->cp_lock, flags);
-                               if (!conn->c_trans->t_mp_capable)
-                                       break;
                        }
                }
        }
@@ -571,15 +586,16 @@ static void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
             i++, head++) {
                hlist_for_each_entry_rcu(conn, head, c_hash_node) {
                        struct rds_conn_path *cp;
+                       int npaths;
 
-                       for (j = 0; j < RDS_MPATH_WORKERS; j++) {
+                       npaths = (conn->c_trans->t_mp_capable ?
+                                RDS_MPATH_WORKERS : 1);
+                       for (j = 0; j < npaths; j++) {
                                cp = &conn->c_path[j];
 
                                /* XXX no cp_lock usage.. */
                                if (!visitor(cp, buffer))
                                        continue;
-                               if (!conn->c_trans->t_mp_capable)
-                                       break;
                        }
 
                        /* We copy as much as we can fit in the buffer,

diff --git a/net/rds/rds.h b/net/rds/rds.h
index 3382695..2e0315b 100644 (file)
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -154,7 +154,7 @@ struct rds_connection {
        struct list_head        c_map_item;
        unsigned long           c_map_queued;
 
-       struct rds_conn_path    c_path[RDS_MPATH_WORKERS];
+       struct rds_conn_path    *c_path;
        wait_queue_head_t       c_hs_waitq; /* handshake waitq */
 
        u32                     c_my_gen_num;