[dpdk-dev,v8,6/7] lib: added new library for latency stats

Message ID 1484695474-1155-7-git-send-email-remy.horton@intel.com
State Superseded, archived
Headers show

Checks

Context Check Description
ci/Intel compilation fail Compilation issues
ci/checkpatch success coding style OK

Commit Message

Remy Horton Jan. 17, 2017, 11:24 p.m.
From: Harry van Haaren <harry.van.haaren@intel.com>

Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
Signed-off-by: Remy Horton <remy.horton@intel.com>
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
---

v7 to v8 changes:
- CYCLES_PER_NS now a static inline function
- "hidden" pthread creation now has polling API instead. The application
  must call rte_latencystats_update() to refresh the values.
- Struct declarations and variable definitions cleaned up
- Double initialization of the library now returns -EEXIST
- MAINTAINERS entry in correct section
- License year updates
---
 MAINTAINERS                                        |   4 +
 config/common_base                                 |   5 +
 doc/api/doxy-api-index.md                          |   1 +
 doc/api/doxy-api.conf                              |   1 +
 doc/guides/rel_notes/release_17_02.rst             |   5 +
 lib/Makefile                                       |   1 +
 lib/librte_latencystats/Makefile                   |  56 ++++
 lib/librte_latencystats/rte_latencystats.c         | 366 +++++++++++++++++++++
 lib/librte_latencystats/rte_latencystats.h         | 154 +++++++++
 .../rte_latencystats_version.map                   |  10 +
 mk/rte.app.mk                                      |   2 +-
 11 files changed, 604 insertions(+), 1 deletion(-)
 create mode 100644 lib/librte_latencystats/Makefile
 create mode 100644 lib/librte_latencystats/rte_latencystats.c
 create mode 100644 lib/librte_latencystats/rte_latencystats.h
 create mode 100644 lib/librte_latencystats/rte_latencystats_version.map

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index d9423cb..03f53b7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -604,6 +604,10 @@  Bit-rate statistica
 M: Remy Horton <remy.horton@intel.com>
 F: lib/librte_bitratestats/
 
+Latency Stats
+M: Reshma Pattan <reshma.pattan@intel.com>
+F: lib/librte_latencystats/
+
 
 Test Applications
 -----------------
diff --git a/config/common_base b/config/common_base
index decebe5..762a54c 100644
--- a/config/common_base
+++ b/config/common_base
@@ -603,3 +603,8 @@  CONFIG_RTE_LIBRTE_METRICS=y
 # Compile the bitrate statistics library
 #
 CONFIG_RTE_LIBRTE_BITRATE=y
+
+#
+# Compile the latency statistics library
+#
+CONFIG_RTE_LIBRTE_LATENCY_STATS=y
diff --git a/doc/api/doxy-api-index.md b/doc/api/doxy-api-index.md
index 5e194b0..1cacacc 100644
--- a/doc/api/doxy-api-index.md
+++ b/doc/api/doxy-api-index.md
@@ -152,4 +152,5 @@  There are many libraries, so their headers may be grouped by topics:
   [keepalive]          (@ref rte_keepalive.h),
   [Device Metrics]     (@ref rte_metrics.h),
   [Bitrate Statistics] (@ref rte_bitrate.h),
+  [Latency stats]      (@ref rte_latencystats.h),
   [version]            (@ref rte_version.h)
diff --git a/doc/api/doxy-api.conf b/doc/api/doxy-api.conf
index 6e6ab5c..0effece 100644
--- a/doc/api/doxy-api.conf
+++ b/doc/api/doxy-api.conf
@@ -47,6 +47,7 @@  INPUT                   = doc/api/doxy-api-index.md \
                           lib/librte_jobstats \
                           lib/librte_kni \
                           lib/librte_kvargs \
+                          lib/librte_latencystats \
                           lib/librte_lpm \
                           lib/librte_mbuf \
                           lib/librte_mempool \
diff --git a/doc/guides/rel_notes/release_17_02.rst b/doc/guides/rel_notes/release_17_02.rst
index 44012c8..29bbd74 100644
--- a/doc/guides/rel_notes/release_17_02.rst
+++ b/doc/guides/rel_notes/release_17_02.rst
@@ -68,6 +68,10 @@  New Features
   Six new APIs have been added to the ixgbe PMD for MACsec offload support.
   The declarations for the APIs can be found in ``rte_pmd_ixgbe.h``.
 
+* **Added latency stats library.**
+
+  A library that measures packet latency. The collected statistics are jitter
+  and latency. For latency the minimum, average, and maximum is measured.
 
 Resolved Issues
 ---------------
@@ -184,6 +188,7 @@  The libraries prepended with a plus sign were incremented in this version.
      librte_jobstats.so.1
      librte_kni.so.2
      librte_kvargs.so.1
+   + librte_latencystats.so.1
      librte_lpm.so.2
      librte_mbuf.so.2
      librte_mempool.so.2
diff --git a/lib/Makefile b/lib/Makefile
index e211bc0..6fffa88 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -60,6 +60,7 @@  DIRS-$(CONFIG_RTE_LIBRTE_REORDER) += librte_reorder
 DIRS-$(CONFIG_RTE_LIBRTE_PDUMP) += librte_pdump
 DIRS-$(CONFIG_RTE_LIBRTE_METRICS) += librte_metrics
 DIRS-$(CONFIG_RTE_LIBRTE_BITRATE) += librte_bitratestats
+DIRS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS) += librte_latencystats
 
 ifeq ($(CONFIG_RTE_EXEC_ENV_LINUXAPP),y)
 DIRS-$(CONFIG_RTE_LIBRTE_KNI) += librte_kni
diff --git a/lib/librte_latencystats/Makefile b/lib/librte_latencystats/Makefile
new file mode 100644
index 0000000..fd145d3
--- /dev/null
+++ b/lib/librte_latencystats/Makefile
@@ -0,0 +1,56 @@ 
+#   BSD LICENSE
+#
+#   Copyright(c) 2016-2017 Intel Corporation. All rights reserved.
+#
+#   Redistribution and use in source and binary forms, with or without
+#   modification, are permitted provided that the following conditions
+#   are met:
+#
+#     * Redistributions of source code must retain the above copyright
+#       notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above copyright
+#       notice, this list of conditions and the following disclaimer in
+#       the documentation and/or other materials provided with the
+#       distribution.
+#     * Neither the name of Intel Corporation nor the names of its
+#       contributors may be used to endorse or promote products derived
+#       from this software without specific prior written permission.
+#
+#   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+#   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+#   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+#   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+#   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+#   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+#   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+#   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+#   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+#   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+#   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+include $(RTE_SDK)/mk/rte.vars.mk
+
+# library name
+LIB = librte_latencystats.a
+
+CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR) -O3
+LDLIBS += -lm
+LDLIBS += -lpthread
+
+EXPORT_MAP := rte_latencystats_version.map
+
+LIBABIVER := 1
+
+# all source are stored in SRCS-y
+SRCS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS) := rte_latencystats.c
+
+# install this header file
+SYMLINK-$(CONFIG_RTE_LIBRTE_LATENCY_STATS)-include := rte_latencystats.h
+
+# this lib depends upon:
+DEPDIRS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS) += lib/librte_mbuf
+DEPDIRS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS) += lib/librte_eal
+DEPDIRS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS) += lib/librte_ether
+DEPDIRS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS) += lib/librte_metrics
+
+include $(RTE_SDK)/mk/rte.lib.mk
diff --git a/lib/librte_latencystats/rte_latencystats.c b/lib/librte_latencystats/rte_latencystats.c
new file mode 100644
index 0000000..5334b8b
--- /dev/null
+++ b/lib/librte_latencystats/rte_latencystats.c
@@ -0,0 +1,366 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2016-2017 Intel Corporation. All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <stdbool.h>
+#include <math.h>
+
+#include <rte_mbuf.h>
+#include <rte_log.h>
+#include <rte_cycles.h>
+#include <rte_ethdev.h>
+#include <rte_metrics.h>
+#include <rte_memzone.h>
+#include <rte_lcore.h>
+#include <rte_timer.h>
+
+#include "rte_latencystats.h"
+
+/** Nano seconds per second */
+#define NS_PER_SEC 1E9
+
+/** Clock cycles per nano second */
+static uint64_t
+latencystat_cycles_per_ns(void)
+{
+	return rte_get_timer_hz() / NS_PER_SEC;
+}
+
+/* Macros for printing using RTE_LOG */
+#define RTE_LOGTYPE_LATENCY_STATS RTE_LOGTYPE_USER1
+
+static const char *MZ_RTE_LATENCY_STATS = "rte_latencystats";
+static int latency_stats_index;
+static uint64_t samp_intvl;
+static uint64_t timer_tsc;
+static uint64_t prev_tsc;
+
+struct rte_latency_stats {
+	float min_latency; /**< Minimum latency in nano seconds */
+	float avg_latency; /**< Average latency in nano seconds */
+	float max_latency; /**< Maximum latency in nano seconds */
+	float jitter; /** Latency variation */
+};
+
+static struct rte_latency_stats *glob_stats;
+
+struct rxtx_cbs {
+	struct rte_eth_rxtx_callback *cb;
+};
+
+static struct rxtx_cbs rx_cbs[RTE_MAX_ETHPORTS][RTE_MAX_QUEUES_PER_PORT];
+static struct rxtx_cbs tx_cbs[RTE_MAX_ETHPORTS][RTE_MAX_QUEUES_PER_PORT];
+
+struct latency_stats_nameoff {
+	char name[RTE_ETH_XSTATS_NAME_SIZE];
+	unsigned int offset;
+};
+
+static const struct latency_stats_nameoff lat_stats_strings[] = {
+	{"min_latency_ns", offsetof(struct rte_latency_stats, min_latency)},
+	{"avg_latency_ns", offsetof(struct rte_latency_stats, avg_latency)},
+	{"max_latency_ns", offsetof(struct rte_latency_stats, max_latency)},
+	{"jitter_ns", offsetof(struct rte_latency_stats, jitter)},
+};
+
+#define NUM_LATENCY_STATS (sizeof(lat_stats_strings) / \
+				sizeof(lat_stats_strings[0]))
+
+int32_t
+rte_latencystats_update(void)
+{
+	unsigned int i;
+	float *stats_ptr = NULL;
+	uint64_t values[NUM_LATENCY_STATS] = {0};
+	int ret;
+
+	for (i = 0; i < NUM_LATENCY_STATS; i++) {
+		stats_ptr = RTE_PTR_ADD(glob_stats,
+				lat_stats_strings[i].offset);
+		values[i] = (uint64_t)floor((*stats_ptr)/
+				latencystat_cycles_per_ns());
+	}
+
+	ret = rte_metrics_update_values(RTE_METRICS_GLOBAL,
+					latency_stats_index,
+					values, NUM_LATENCY_STATS);
+	if (ret < 0)
+		RTE_LOG(INFO, LATENCY_STATS, "Failed to push the stats\n");
+
+	return ret;
+}
+
+static void
+rte_latencystats_fill_values(struct rte_metric_value *values)
+{
+	unsigned int i;
+	float *stats_ptr = NULL;
+
+	for (i = 0; i < NUM_LATENCY_STATS; i++) {
+		stats_ptr = RTE_PTR_ADD(glob_stats,
+				lat_stats_strings[i].offset);
+		values[i].key = i;
+		values[i].value = (uint64_t)floor((*stats_ptr)/
+						latencystat_cycles_per_ns());
+	}
+}
+
+static uint16_t
+add_time_stamps(uint8_t pid __rte_unused,
+		uint16_t qid __rte_unused,
+		struct rte_mbuf **pkts,
+		uint16_t nb_pkts,
+		uint16_t max_pkts __rte_unused,
+		void *user_cb __rte_unused)
+{
+	unsigned int i;
+	uint64_t diff_tsc, now;
+
+	/*
+	 * For every sample interval,
+	 * time stamp is marked on one received packet.
+	 */
+	now = rte_rdtsc();
+	for (i = 0; i < nb_pkts; i++) {
+		diff_tsc = now - prev_tsc;
+		timer_tsc += diff_tsc;
+		if (timer_tsc >= samp_intvl) {
+			/*
+			 * TBD: Mark the timestamp only
+			 * if not already marked by the
+			 * hardware or the PMD.
+			 */
+			pkts[i]->timestamp = now;
+			timer_tsc = 0;
+		}
+		prev_tsc = now;
+		now = rte_rdtsc();
+	}
+
+	return nb_pkts;
+}
+
+static uint16_t
+calc_latency(uint8_t pid __rte_unused,
+		uint16_t qid __rte_unused,
+		struct rte_mbuf **pkts,
+		uint16_t nb_pkts,
+		void *_ __rte_unused)
+{
+	unsigned int i, cnt = 0;
+	uint64_t now;
+	float latency[nb_pkts];
+	static float prev_latency;
+	/*
+	 * Alpha represents degree of weighting decrease in EWMA,
+	 * a constant smoothing factor between 0 and 1. The value
+	 * is used below for measuring average latency.
+	 */
+	const float alpha = 0.2;
+
+	now = rte_rdtsc();
+	for (i = 0; i < nb_pkts; i++) {
+		if (pkts[i]->timestamp)
+			latency[cnt++] = now - pkts[i]->timestamp;
+	}
+
+	for (i = 0; i < cnt; i++) {
+		/*
+		 * The jitter is calculated as statistical mean of interpacket
+		 * delay variation. The "jitter estimate" is computed by taking
+		 * the absolute values of the ipdv sequence and applying an
+		 * exponential filter with parameter 1/16 to generate the
+		 * estimate. i.e J=J+(|D(i-1,i)|-J)/16. Where J is jitter,
+		 * D(i-1,i) is difference in latency of two consecutive packets
+		 * i-1 and i.
+		 * Reference: Calculated as per RFC 5481, sec 4.1,
+		 * RFC 3393 sec 4.5, RFC 1889 sec.
+		 */
+		glob_stats->jitter +=  (abs(prev_latency - latency[i])
+					- glob_stats->jitter)/16;
+		if (glob_stats->min_latency == 0)
+			glob_stats->min_latency = latency[i];
+		else if (latency[i] < glob_stats->min_latency)
+			glob_stats->min_latency = latency[i];
+		else if (latency[i] > glob_stats->max_latency)
+			glob_stats->max_latency = latency[i];
+		/*
+		 * The average latency is measured using exponential moving
+		 * average, i.e. using EWMA
+		 * https://en.wikipedia.org/wiki/Moving_average
+		 */
+		glob_stats->avg_latency +=
+			alpha * (latency[i] - glob_stats->avg_latency);
+		prev_latency = latency[i];
+	}
+
+	return nb_pkts;
+}
+
+int
+rte_latencystats_init(uint64_t app_samp_intvl,
+		rte_latency_stats_flow_type_fn user_cb)
+{
+	unsigned int i;
+	uint8_t pid;
+	uint16_t qid;
+	struct rxtx_cbs *cbs = NULL;
+	const uint8_t nb_ports = rte_eth_dev_count();
+	const char *ptr_strings[NUM_LATENCY_STATS] = {0};
+	const struct rte_memzone *mz = NULL;
+	const unsigned int flags = 0;
+
+	if (rte_memzone_lookup(MZ_RTE_LATENCY_STATS))
+		return -EEXIST;
+
+	/** Allocate stats in shared memory fo multi process support */
+	mz = rte_memzone_reserve(MZ_RTE_LATENCY_STATS, sizeof(*glob_stats),
+					rte_socket_id(), flags);
+	if (mz == NULL) {
+		RTE_LOG(ERR, LATENCY_STATS, "Cannot reserve memory: %s:%d\n",
+			__func__, __LINE__);
+		return -ENOMEM;
+	}
+
+	glob_stats = mz->addr;
+	samp_intvl = app_samp_intvl * latencystat_cycles_per_ns();
+
+	/** Register latency stats with stats library */
+	for (i = 0; i < NUM_LATENCY_STATS; i++)
+		ptr_strings[i] = lat_stats_strings[i].name;
+
+	latency_stats_index = rte_metrics_reg_names(ptr_strings,
+							NUM_LATENCY_STATS);
+	if (latency_stats_index < 0) {
+		RTE_LOG(DEBUG, LATENCY_STATS,
+			"Failed to register latency stats names\n");
+		return -1;
+	}
+
+	/** Register Rx/Tx callbacks */
+	for (pid = 0; pid < nb_ports; pid++) {
+		struct rte_eth_dev_info dev_info;
+		rte_eth_dev_info_get(pid, &dev_info);
+		for (qid = 0; qid < dev_info.nb_rx_queues; qid++) {
+			cbs = &rx_cbs[pid][qid];
+			cbs->cb = rte_eth_add_first_rx_callback(pid, qid,
+					add_time_stamps, user_cb);
+			if (!cbs->cb)
+				RTE_LOG(INFO, LATENCY_STATS, "Failed to "
+					"register Rx callback for pid=%d, "
+					"qid=%d\n", pid, qid);
+		}
+		for (qid = 0; qid < dev_info.nb_tx_queues; qid++) {
+			cbs = &tx_cbs[pid][qid];
+			cbs->cb =  rte_eth_add_tx_callback(pid, qid,
+					calc_latency, user_cb);
+			if (!cbs->cb)
+				RTE_LOG(INFO, LATENCY_STATS, "Failed to "
+					"register Tx callback for pid=%d, "
+					"qid=%d\n", pid, qid);
+		}
+	}
+	return 0;
+}
+
+int
+rte_latencystats_uninit(void)
+{
+	uint8_t pid;
+	uint16_t qid;
+	int ret = 0;
+	struct rxtx_cbs *cbs = NULL;
+	const uint8_t nb_ports = rte_eth_dev_count();
+
+	/** De register Rx/Tx callbacks */
+	for (pid = 0; pid < nb_ports; pid++) {
+		struct rte_eth_dev_info dev_info;
+		rte_eth_dev_info_get(pid, &dev_info);
+		for (qid = 0; qid < dev_info.nb_rx_queues; qid++) {
+			cbs = &rx_cbs[pid][qid];
+			ret = rte_eth_remove_rx_callback(pid, qid, cbs->cb);
+			if (ret)
+				RTE_LOG(INFO, LATENCY_STATS, "failed to "
+					"remove Rx callback for pid=%d, "
+					"qid=%d\n", pid, qid);
+		}
+		for (qid = 0; qid < dev_info.nb_tx_queues; qid++) {
+			cbs = &tx_cbs[pid][qid];
+			ret = rte_eth_remove_tx_callback(pid, qid, cbs->cb);
+			if (ret)
+				RTE_LOG(INFO, LATENCY_STATS, "failed to "
+					"remove Tx callback for pid=%d, "
+					"qid=%d\n", pid, qid);
+		}
+	}
+
+	return 0;
+}
+
+int
+rte_latencystats_get_names(struct rte_metric_name *names, uint16_t size)
+{
+	unsigned int i;
+
+	if (names == NULL || size < NUM_LATENCY_STATS)
+		return NUM_LATENCY_STATS;
+
+	for (i = 0; i < NUM_LATENCY_STATS; i++)
+		snprintf(names[i].name, sizeof(names[i].name),
+				"%s", lat_stats_strings[i].name);
+
+	return NUM_LATENCY_STATS;
+}
+
+int
+rte_latencystats_get(struct rte_metric_value *values, uint16_t size)
+{
+	if (size < NUM_LATENCY_STATS || values == NULL)
+		return NUM_LATENCY_STATS;
+
+	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
+		const struct rte_memzone *mz;
+		mz = rte_memzone_lookup(MZ_RTE_LATENCY_STATS);
+		if (mz == NULL) {
+			RTE_LOG(ERR, LATENCY_STATS,
+				"Latency stats memzone not found\n");
+			return -ENOMEM;
+		}
+		glob_stats =  mz->addr;
+	}
+
+	/* Retrieve latency stats */
+	rte_latencystats_fill_values(values);
+
+	return NUM_LATENCY_STATS;
+}
diff --git a/lib/librte_latencystats/rte_latencystats.h b/lib/librte_latencystats/rte_latencystats.h
new file mode 100644
index 0000000..28c6dcf
--- /dev/null
+++ b/lib/librte_latencystats/rte_latencystats.h
@@ -0,0 +1,154 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2016-2017 Intel Corporation. All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _RTE_LATENCYSTATS_H_
+#define _RTE_LATENCYSTATS_H_
+
+/**
+ * @file
+ * RTE latency stats
+ *
+ * library to provide application and flow based latency stats.
+ */
+
+#include <rte_metrics.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  Note: This function pointer is for future flow based latency stats
+ *  implementation.
+ *
+ * Function type used for identifting flow types of a Rx packet.
+ *
+ * The callback function is called on Rx for each packet.
+ * This function is used for flow based latency calculations.
+ *
+ * @param pkt
+ *   Packet that has to be identified with its flow types.
+ * @param user_param
+ *   The arbitrary user parameter passed in by the application when
+ *   the callback was originally configured.
+ * @return
+ *   The flow_mask, representing the multiple flow types of a packet.
+ */
+typedef uint16_t (*rte_latency_stats_flow_type_fn)(struct rte_mbuf *pkt,
+							void *user_param);
+
+/**
+ *  Registers Rx/Tx callbacks for each active port, queue.
+ *
+ * @param samp_intvl
+ *  Sampling time period in nano seconds, at which packet
+ *  should be marked with time stamp.
+ * @param user_cb
+ *  Note: This param is for future flow based latency stats
+ *  implementation.
+ *  User callback to be called to get flow types of a packet.
+ *  Used for flow based latency calculation.
+ *  If the value is NULL, global stats will be calculated,
+ *  else flow based latency stats will be calculated.
+ *  For now just pass on the NULL value to this param.
+ *  @return
+ *   -1     : On error
+ *   -ENOMEM: On error
+ *    0     : On success
+ */
+int rte_latencystats_init(uint64_t samp_intvl,
+			rte_latency_stats_flow_type_fn user_cb);
+
+/**
+ * Calculates the latency and jitter values internally, exposing the updated
+ * values via *rte_latencystats_get* or the rte_metrics API.
+ * @return:
+ *  0      : on Success
+ *  < 0    : Error in updating values.
+ */
+int32_t rte_latencystats_update(void);
+
+/**
+ *  Removes registered Rx/Tx callbacks for each active port, queue.
+ *
+ *  @return
+ *   -1: On error
+ *    0: On success
+ */
+int rte_latencystats_uninit(void);
+
+/**
+ * Retrieve names of latency statistics
+ *
+ * @param names
+ *  Block of memory to insert names into. Must be at least size in capacity.
+ *  If set to NULL, function returns required capacity.
+ * @param size
+ *  Capacity of latency stats names (number of names).
+ * @return
+ *   - positive value lower or equal to size: success. The return value
+ *     is the number of entries filled in the stats table.
+ *   - positive value higher than size: error, the given statistics table
+ *     is too small. The return value corresponds to the size that should
+ *     be given to succeed. The entries in the table are not valid and
+ *     shall not be used by the caller.
+ */
+int rte_latencystats_get_names(struct rte_metric_name *names,
+				uint16_t size);
+
+/**
+ * Retrieve latency statistics.
+ *
+ * @param values
+ *   A pointer to a table of structure of type *rte_metric_value*
+ *   to be filled with latency statistics ids and values.
+ *   This parameter can be set to NULL if size is 0.
+ * @param size
+ *   The size of the stats table, which should be large enough to store
+ *   all the latency stats.
+ * @return
+ *   - positive value lower or equal to size: success. The return value
+ *     is the number of entries filled in the stats table.
+ *   - positive value higher than size: error, the given statistics table
+ *     is too small. The return value corresponds to the size that should
+ *     be given to succeed. The entries in the table are not valid and
+ *     shall not be used by the caller.
+ *   -ENOMEM: On failure.
+ */
+int rte_latencystats_get(struct rte_metric_value *values,
+			uint16_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_LATENCYSTATS_H_ */
diff --git a/lib/librte_latencystats/rte_latencystats_version.map b/lib/librte_latencystats/rte_latencystats_version.map
new file mode 100644
index 0000000..502018e
--- /dev/null
+++ b/lib/librte_latencystats/rte_latencystats_version.map
@@ -0,0 +1,10 @@ 
+DPDK_17.02 {
+	global:
+
+	rte_latencystats_get;
+	rte_latencystats_get_names;
+	rte_latencystats_init;
+	rte_latencystats_uninit;
+
+	local: *;
+};
diff --git a/mk/rte.app.mk b/mk/rte.app.mk
index 6aac5ac..1d36fad 100644
--- a/mk/rte.app.mk
+++ b/mk/rte.app.mk
@@ -100,7 +100,7 @@  _LDLIBS-$(CONFIG_RTE_LIBRTE_CMDLINE)        += -lrte_cmdline
 _LDLIBS-$(CONFIG_RTE_LIBRTE_CFGFILE)        += -lrte_cfgfile
 _LDLIBS-$(CONFIG_RTE_LIBRTE_METRICS)        += -lrte_metrics
 _LDLIBS-$(CONFIG_RTE_LIBRTE_BITRATE)        += -lrte_bitratestats
-
+_LDLIBS-$(CONFIG_RTE_LIBRTE_LATENCY_STATS)  += -lrte_latencystats
 
 _LDLIBS-$(CONFIG_RTE_LIBRTE_PMD_BOND)       += -lrte_pmd_bond
 _LDLIBS-$(CONFIG_RTE_LIBRTE_PMD_XENVIRT)    += -lrte_pmd_xenvirt -lxenstore