[dpdk-dev] [PATCH] ether: add support for vtune task tracing

[ilia.kurakin at intel.com]

From: Ilia Kurakin <ilia.kurakin at intel.com>

The patch adds tracing of loop iterations that yielded no packets in a DPDK
application. It is using ITT task API:
    https://software.intel.com/en-us/node/544206

We suppose the flow of using this tracing would assume the user has ITT lib
and header on his machine and re-build DPDK with additional make parameters:

    make EXTRA_CFLAGS=-I<path to ittnotify.h>
         EXTRA_LDLIBS="-L<path to libittnotify.a> -littnotify"

Signed-off-by: Ilia Kurakin <ilia.kurakin at intel.com>
---
 config/common_base             |  1 +
 lib/librte_ether/Makefile      |  1 +
 lib/librte_ether/rte_eth_itt.h | 69 ++++++++++++++++++++++++++++++++++++++++++
 lib/librte_ether/rte_ethdev.c  |  7 +++++
 lib/librte_ether/rte_ethdev.h  | 26 ++++++++++++++++
 5 files changed, 104 insertions(+)
 create mode 100644 lib/librte_ether/rte_eth_itt.h

diff --git a/config/common_base b/config/common_base
index f6aafd1..60d8b63 100644
--- a/config/common_base
+++ b/config/common_base
@@ -135,6 +135,7 @@ CONFIG_RTE_MAX_QUEUES_PER_PORT=1024
 CONFIG_RTE_LIBRTE_IEEE1588=n
 CONFIG_RTE_ETHDEV_QUEUE_STAT_CNTRS=16
 CONFIG_RTE_ETHDEV_RXTX_CALLBACKS=y
+CONFIG_RTE_ETHDEV_TRACE_WASTED_RX_ITERATIONS=n
 
 #
 # Turn off Tx preparation stage
diff --git a/lib/librte_ether/Makefile b/lib/librte_ether/Makefile
index 93fdde1..c10153a 100644
--- a/lib/librte_ether/Makefile
+++ b/lib/librte_ether/Makefile
@@ -56,5 +56,6 @@ SYMLINK-y-include += rte_eth_ctrl.h
 SYMLINK-y-include += rte_dev_info.h
 SYMLINK-y-include += rte_flow.h
 SYMLINK-y-include += rte_flow_driver.h
+SYMLINK-${CONFIG_RTE_ETHDEV_TRACE_WASTED_RX_ITERATIONS}-include += rte_eth_itt.h
 
 include $(RTE_SDK)/mk/rte.lib.mk
diff --git a/lib/librte_ether/rte_eth_itt.h b/lib/librte_ether/rte_eth_itt.h
new file mode 100644
index 0000000..e7984fb
--- /dev/null
+++ b/lib/librte_ether/rte_eth_itt.h
@@ -0,0 +1,69 @@
+#ifndef _RTE_ETH_ITT_H_
+#define _RTE_ETH_ITT_H_
+
+#include <ittnotify.h>
+#include <rte_config.h>
+
+#define ITT_MAX_NAME_LEN (100)
+
+/**
+ * Auxiliary ITT structure belonging to port and using to:
+ *   -  track queue state to determine whether it is wasting loop iterations
+ *   -  begin or end ITT task using task domain and name
+ */
+struct rte_eth_itt_aux_data {
+	/**
+	 * ITT domains for each queue.
+	 */
+	__itt_domain *wasted_iteration_itt_domains[RTE_MAX_QUEUES_PER_PORT];
+	/**
+	 * ITT task names for each queue.
+	 */
+	__itt_string_handle *wasted_iteration_itt_handles[RTE_MAX_QUEUES_PER_PORT];
+	/**
+	 * Flags indicating the queues state. Possible values:
+	 * 1 - queue is wasting iterations, 0 - otherwise.
+	 */
+	uint8_t queue_is_wasting_iterations[RTE_MAX_QUEUES_PER_PORT];
+};
+
+/**
+ * The pool of *rte_eth_itt_aux_data* structures.
+ */
+struct rte_eth_itt_aux_data itt_aux_data[RTE_MAX_ETHPORTS];
+
+/**
+ * Initialization of rte_eth_itt_aux_data for a given port.
+ * This function must be invoked when ethernet device is being configured.
+ * Result will be stored in the global array *itt_aux_data*.
+ *
+ * @param port_id
+ *  The port identifier of the Ethernet device.
+ * @param port_name
+ *  The name of the Ethernet device.
+ * @param queue_num
+ *  The number of queues on specified port.
+ */
+static inline void
+rte_eth_init_itt(uint8_t port_id, char *port_name, uint8_t queue_num) {
+	uint16_t q_id;
+	for (q_id = 0; q_id < queue_num; ++q_id) {
+		char domain_name[ITT_MAX_NAME_LEN];
+		snprintf(domain_name, sizeof(domain_name),
+			"RXBurst.WastedIterations.Port_%s.Queue_%d",
+			port_name, q_id);
+		itt_aux_data[port_id].wasted_iteration_itt_domains[q_id]
+			= __itt_domain_create(domain_name);
+
+		char task_name[ITT_MAX_NAME_LEN];
+		snprintf(task_name, sizeof(task_name),
+			"port id: %d; queue id: %d",
+			port_id, q_id);
+		itt_aux_data[port_id].wasted_iteration_itt_handles[q_id]
+			= __itt_string_handle_create(task_name);
+
+		itt_aux_data[port_id].queue_is_wasting_iterations[q_id] = 0;
+	}
+}
+
+#endif
diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
index 81a45c0..9e5ac01 100644
--- a/lib/librte_ether/rte_ethdev.c
+++ b/lib/librte_ether/rte_ethdev.c
@@ -818,6 +818,13 @@ rte_eth_dev_configure(uint8_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 		return diag;
 	}
 
+#ifdef RTE_ETHDEV_TRACE_WASTED_RX_ITERATIONS
+	/**
+	* See rte_eth_itt.h to find comments on code below.
+	*/
+	rte_eth_init_itt(port_id, dev->data->name, nb_rx_q);
+#endif
+
 	return 0;
 }
 
diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index f6e6c74..4ba90d2 100644
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -186,6 +186,10 @@ extern "C" {
 #include "rte_eth_ctrl.h"
 #include "rte_dev_info.h"
 
+#ifdef RTE_ETHDEV_TRACE_WASTED_RX_ITERATIONS
+#include "rte_eth_itt.h"
+#endif
+
 struct rte_mbuf;
 
 /**
@@ -2710,6 +2714,28 @@ rte_eth_rx_burst(uint8_t port_id, uint16_t queue_id,
 	int16_t nb_rx = (*dev->rx_pkt_burst)(dev->data->rx_queues[queue_id],
 			rx_pkts, nb_pkts);
 
+#ifdef RTE_ETHDEV_TRACE_WASTED_RX_ITERATIONS
+	/**
+	* See rte_eth_itt.h to find comments on code below.
+	*/
+	if (unlikely(nb_rx == 0)) {
+		if (!itt_aux_data[port_id].queue_is_wasting_iterations[queue_id]) {
+			__itt_task_begin(
+				itt_aux_data[port_id].wasted_iteration_itt_domains[queue_id],
+				__itt_null, __itt_null,
+				itt_aux_data[port_id].wasted_iteration_itt_handles[queue_id]);
+			itt_aux_data[port_id].queue_is_wasting_iterations[queue_id] = 1;
+		}
+	}
+	else {
+		if (unlikely(itt_aux_data[port_id].queue_is_wasting_iterations[queue_id])) {
+			__itt_task_end(
+				itt_aux_data[port_id].wasted_iteration_itt_domains[queue_id]);
+			itt_aux_data[port_id].queue_is_wasting_iterations[queue_id] = 0;
+		}
+	}
+#endif
+
 #ifdef RTE_ETHDEV_RXTX_CALLBACKS
 	struct rte_eth_rxtx_callback *cb = dev->post_rx_burst_cbs[queue_id];
 
-- 
2.7.4


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