[PATCH rdma-next v1 1/4] IB/mlx5: Introduce ODP diagnostic counters

[Leon Romanovsky <leon@kernel.org>]

From: Erez Alfasi <ereza@mellanox.com>

Introduce ODP diagnostic counters and count the following
per MR within IB/mlx5 driver:
 1) Page faults:
	Total number of faulted pages.
 2) Page invalidations:
	Total number of pages invalidated by the OS during all
	invalidation events. The translations can be no longer
	valid due to either non-present pages or mapping changes.
 3) Prefetched pages:
	When prefetching a page, page fault is generated
	in order to bring the page to the main memory.
	The prefetched pages counter will be updated
	during a page fault flow only if it was derived
	from prefetching operation.

Signed-off-by: Erez Alfasi <ereza@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
---
 drivers/infiniband/hw/mlx5/odp.c | 18 ++++++++++++++++++
 include/rdma/ib_umem_odp.h       | 14 ++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 905936423a03..b7c8a49ac753 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -287,6 +287,10 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
 
 	ib_umem_odp_unmap_dma_pages(umem_odp, start, end);
 
+	/* Count page invalidations */
+	ib_update_odp_stats(umem_odp, invalidations,
+			    ib_umem_odp_num_pages(umem_odp));
+
 	if (unlikely(!umem_odp->npages && mr->parent &&
 		     !umem_odp->dying)) {
 		WRITE_ONCE(umem_odp->dying, 1);
@@ -801,6 +805,20 @@ static int pagefault_single_data_segment(struct mlx5_ib_dev *dev,
 		if (ret < 0)
 			goto srcu_unlock;
 
+		/*
+		 * When prefetching a page, page fault is generated
+		 * in order to bring the page to the main memory.
+		 * In the current flow, page faults are being counted.
+		 * Prefetched pages counter will be updated as well
+		 * only if the current page fault flow was derived
+		 * from prefetching flow.
+		 */
+		ib_update_odp_stats(to_ib_umem_odp(mr->umem), faults, ret);
+
+		if (prefetch)
+			ib_update_odp_stats(to_ib_umem_odp(mr->umem),
+					    prefetched, ret);
+
 		npages += ret;
 		ret = 0;
 		break;
diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
index b37c674b7fe6..3359e34516da 100644
--- a/include/rdma/ib_umem_odp.h
+++ b/include/rdma/ib_umem_odp.h
@@ -37,6 +37,12 @@
 #include <rdma/ib_verbs.h>
 #include <linux/interval_tree.h>
 
+struct ib_odp_counters {
+	atomic64_t faults;
+	atomic64_t invalidations;
+	atomic64_t prefetched;
+};
+
 struct ib_umem_odp {
 	struct ib_umem umem;
 	struct ib_ucontext_per_mm *per_mm;
@@ -62,6 +68,11 @@ struct ib_umem_odp {
 	struct mutex		umem_mutex;
 	void			*private; /* for the HW driver to use. */
 
+	/*
+	 * ODP diagnostic counters.
+	 */
+	struct ib_odp_counters odp_stats;
+
 	int notifiers_seq;
 	int notifiers_count;
 	int npages;
@@ -106,6 +117,9 @@ static inline size_t ib_umem_odp_num_pages(struct ib_umem_odp *umem_odp)
 	       umem_odp->page_shift;
 }
 
+#define ib_update_odp_stats(umem_odp, counter_name, value)		    \
+	atomic64_add(value, &(umem_odp->odp_stats.counter_name))
+
 /*
  * The lower 2 bits of the DMA address signal the R/W permissions for
  * the entry. To upgrade the permissions, provide the appropriate
-- 
2.20.1