From 9ead190bfde2a434c74ea604382d08acb2eceef5 Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Sat, 17 Jun 2006 20:44:49 -0700 Subject: IB/uverbs: Don't serialize with ib_uverbs_idr_mutex Currently, all userspace verbs operations that call into the kernel are serialized by ib_uverbs_idr_mutex. This can be a scalability issue for some workloads, especially for devices driven by the ipath driver, which needs to call into the kernel even for datapath operations. Fix this by adding reference counts to the userspace objects, and then converting ib_uverbs_idr_mutex into a spinlock that only protects the idrs long enough to take a reference on the object being looked up. Because remove operations may fail, we have to do a slightly funky two-step deletion, which is described in the comments at the top of uverbs_cmd.c. This also still leaves ib_uverbs_idr_lock as a single lock that is possibly subject to contention. However, the lock hold time will only be a single idr operation, so multiple threads should still be able to make progress, even if ib_uverbs_idr_lock is being ping-ponged. Surprisingly, these changes even shrink the object code: add/remove: 23/5 grow/shrink: 4/21 up/down: 633/-693 (-60) Signed-off-by: Roland Dreier --- include/rdma/ib_verbs.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/rdma') diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h index 7ced208edacf..ee1f3a355666 100644 --- a/include/rdma/ib_verbs.h +++ b/include/rdma/ib_verbs.h @@ -697,8 +697,12 @@ struct ib_ucontext { struct ib_uobject { u64 user_handle; /* handle given to us by userspace */ struct ib_ucontext *context; /* associated user context */ + void *object; /* containing object */ struct list_head list; /* link to context's list */ u32 id; /* index into kernel idr */ + struct kref ref; + struct rw_semaphore mutex; /* protects .live */ + int live; }; struct ib_umem { -- cgit v1.2.3-59-g8ed1b