RDS/IB: Add caching of frags and incs

This patch is based heavily on an initial patch by Chris Mason.
Instead of freeing slab memory and pages, it keeps them, and
funnels them back to be reused.

The lock minimization strategy uses xchg and cmpxchg atomic ops
for manipulation of pointers to list heads. We anchor the lists with a
pointer to a list_head struct instead of a static list_head struct.
We just have to carefully use the existing primitives with
the difference between a pointer and a static head struct.

For example, 'list_empty()' means that our anchor pointer points to a list with
a single item instead of meaning that our static head element doesn't point to
any list items.

Original patch by Chris, with significant mods and fixes by Andy and Zach.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: Zach Brown <zach.brown@oracle.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index a9fb917c00b..10f6a8815cd 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -709,12 +709,19 @@ int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 {
 	struct rds_ib_connection *ic;
 	unsigned long flags;
+	int ret;
 
 	/* XXX too lazy? */
 	ic = kzalloc(sizeof(struct rds_ib_connection), GFP_KERNEL);
 	if (!ic)
 		return -ENOMEM;
 
+	ret = rds_ib_recv_alloc_caches(ic);
+	if (ret) {
+		kfree(ic);
+		return ret;
+	}
+
 	INIT_LIST_HEAD(&ic->ib_node);
 	tasklet_init(&ic->i_recv_tasklet, rds_ib_recv_tasklet_fn,
 		     (unsigned long) ic);
@@ -763,6 +770,8 @@ void rds_ib_conn_free(void *arg)
 	list_del(&ic->ib_node);
 	spin_unlock_irq(lock_ptr);
 
+	rds_ib_recv_free_caches(ic);
+
 	kfree(ic);
 }