[dpdk-dev] [PATCH] [RFC] vhost: inroduce operation to get vDPA queue stats

[Matan Azrad <matan@mellanox.com>]

The vDPA device offloads all the datapath of the vhost device to the HW
device.

In order to expose to the user traffic information this patch introduce
new API to get traffic statistics per virtio queue.

The statistics are taken directly from the vDPA driver managing the HW
device.

Signed-off-by: Matan Azrad <matan@mellanox.com>
---
 lib/librte_vhost/rte_vdpa.h            | 45 +++++++++++++++++++++++++++++++++-
 lib/librte_vhost/rte_vhost_version.map |  1 +
 lib/librte_vhost/vdpa.c                | 14 +++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)


The statistics are very important to reflect some information to the application on traffic.
Please review it and comment.

Thanks!

diff --git a/lib/librte_vhost/rte_vdpa.h b/lib/librte_vhost/rte_vdpa.h
index 9a3deb3..595da76 100644
--- a/lib/librte_vhost/rte_vdpa.h
+++ b/lib/librte_vhost/rte_vdpa.h
@@ -37,6 +37,27 @@ struct rte_vdpa_dev_addr {
 	};
 };
 
+struct rte_vdpa_queue_stats {
+	/** Number of descriptors received by device */
+	uint64_t recieved_desc;
+	/** Number of descriptors completed by the device */
+	uint64_t completed_desc;
+	/** Number of bad descriptors received by device */
+	uint32_t bad_desc;
+	/**
+	 * Number of chained descriptors received that exceed the max allowed
+	 * chain by device
+	 */
+	uint32_t exceed_max_chain;
+	/**
+	 * Number of times device tried to read or write buffer that is not
+	 * registered to the device
+	 */
+	uint32_t invalid_buffer;
+	/** Number of errors detected by the device */
+	uint32_t errors;
+};
+
 /**
  * vdpa device operations
  */
@@ -73,8 +94,11 @@ struct rte_vdpa_dev_ops {
 	int (*get_notify_area)(int vid, int qid,
 			uint64_t *offset, uint64_t *size);
 
+	/** Get statistics of the queue */
+	int (*get_stats)(int did, int qid, struct rte_vdpa_queue_stats *stats);
+
 	/** Reserved for future extension */
-	void *reserved[5];
+	void *reserved[4];
 };
 
 /**
@@ -200,4 +224,23 @@ struct rte_vdpa_device *
 __rte_experimental
 int
 rte_vdpa_relay_vring_used(int vid, uint16_t qid, void *vring_m);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Get vDPA device queue statistics.
+ *
+ * @param did
+ *  device id
+ * @param qid
+ *  queue id
+ * @param stats
+ *  queue statistics pointer.
+ * @return
+ *  0 on success, non-zero on failure.
+ */
+__rte_experimental
+int
+rte_vdpa_get_stats(int did, uint16_t qid, struct rte_vdpa_queue_stats *stats);
 #endif /* _RTE_VDPA_H_ */
diff --git a/lib/librte_vhost/rte_vhost_version.map b/lib/librte_vhost/rte_vhost_version.map
index 051d08c..c9dcff4 100644
--- a/lib/librte_vhost/rte_vhost_version.map
+++ b/lib/librte_vhost/rte_vhost_version.map
@@ -38,6 +38,7 @@ EXPERIMENTAL {
 	rte_vdpa_find_device_id;
 	rte_vdpa_get_device;
 	rte_vdpa_get_device_num;
+	rte_vdpa_get_stats;
 	rte_vhost_driver_attach_vdpa_device;
 	rte_vhost_driver_detach_vdpa_device;
 	rte_vhost_driver_get_vdpa_device_id;
diff --git a/lib/librte_vhost/vdpa.c b/lib/librte_vhost/vdpa.c
index 2b86708..57900fc 100644
--- a/lib/librte_vhost/vdpa.c
+++ b/lib/librte_vhost/vdpa.c
@@ -227,3 +227,17 @@ struct rte_vdpa_device *
 		free_ind_table(idesc);
 	return -1;
 }
+
+int
+rte_vdpa_get_stats(int did, uint16_t qid, struct rte_vdpa_queue_stats *stats)
+{
+	struct rte_vdpa_device *vdpa_dev;
+
+	vdpa_dev = rte_vdpa_get_device(did);
+	if (!vdpa_dev)
+		return -ENODEV;
+
+	RTE_FUNC_PTR_OR_ERR_RET(vdpa_dev->ops->get_stats, -ENOTSUP);
+
+	return vdpa_dev->ops->get_stats(did, qid, stats);
+}
-- 
1.8.3.1