From d144da8c6f51f48ec39d891ea9dff80169c45f3b Mon Sep 17 00:00:00 2001 From: Mike Marciniszyn Date: Mon, 2 Nov 2015 12:13:25 -0500 Subject: IB/core: use RCU for uverbs id lookup The current implementation gets a spin_lock, and at any scale with qib and hfi1 post send, the lock contention grows exponentially with the number of QPs. idr_find() is RCU compatibile, so read doesn't need the lock. Change to use rcu_read_lock() and rcu_read_unlock() in __idr_get_uobj(). kfree_rcu() is used to insure a grace period between the idr removal and actual free. Reviewed-by: Ira Weiny Signed-off-by: Mike Marciniszyn Reviewed-By: Jason Gunthorpe Signed-off-by: Doug Ledford --- include/rdma/ib_verbs.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/rdma') diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index 9a68a19532ba..120da1d7f57e 100644 --- a/include/rdma/ib_verbs.h +++ b/include/rdma/ib_verbs.h @@ -1271,6 +1271,7 @@ struct ib_uobject { int id; /* index into kernel idr */ struct kref ref; struct rw_semaphore mutex; /* protects .live */ + struct rcu_head rcu; /* kfree_rcu() overhead */ int live; }; -- cgit v1.2.3