IB/hfi1: Add unique txwait_lock for txreq events

Profiling suggests that the read_seqbegin() in
the txreq put logic is colliding with other uses
of the iowait lock.

The packet at a time use of this lock dictates a unique
lock to avoid reader/writer collisions when the number
of vTxWait events is low.

In order to support a unique lock the iowait struct embedded
in the QP is extended to remember the lock that protects the queue
head.

The QP destroy removes that QP from any wait list.  It doesn't
need to know the head because of the linked list API, but it does
need to know the lock required to protect the head.

This also opens up the wait logic to have unique per resources locks
which needs to be in future refinement.

Reviewed-by: Sebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/infiniband/hw/hfi1/verbs.h b/drivers/infiniband/hw/hfi1/verbs.h
index 1c3815d..7a8af39 100644
--- a/drivers/infiniband/hw/hfi1/verbs.h
+++ b/drivers/infiniband/hw/hfi1/verbs.h
@@ -180,18 +180,19 @@ struct hfi1_ibdev {
 	struct rvt_dev_info rdi; /* Must be first */
 
 	/* QP numbers are shared by all IB ports */
-	/* protect wait lists */
-	seqlock_t iowait_lock;
+	/* protect txwait list */
+	seqlock_t txwait_lock ____cacheline_aligned_in_smp;
 	struct list_head txwait;        /* list for wait verbs_txreq */
 	struct list_head memwait;       /* list for wait kernel memory */
-	struct list_head txreq_free;
 	struct kmem_cache *verbs_txreq_cache;
-	struct timer_list mem_timer;
+	u64 n_txwait;
+	u64 n_kmem_wait;
 
+	/* protect iowait lists */
+	seqlock_t iowait_lock ____cacheline_aligned_in_smp;
 	u64 n_piowait;
 	u64 n_piodrain;
-	u64 n_txwait;
-	u64 n_kmem_wait;
+	struct timer_list mem_timer;
 
 #ifdef CONFIG_DEBUG_FS
 	/* per HFI debugfs */