[dpdk-dev] [PATCH v3 0/3] Add rte_eth_read_clock API

[dpdk-dev] [PATCH v3 0/3] Add rte_eth_read_clock API

[Tom Barbette]

Some NICs allow to timestamp packets, but do not support the full
PTP synchronization process. Hence, the value set in the mbuf
timestamp field is only the raw value of an internal clock.

To make sense of this value, one at least needs to be able to query
the current hardware clock value. This patch series adds a new API to do
so, rte_eth_read_clock. As with the TSC, from there
a frequency can be derieved by querying multiple time the current value of the
internal clock with some known delay between the queries (example
provided in the API doc).

This patch series adds support of read_clock for MLX5.

An example app is provided in the rxtx_callback application.
It has been updated to display, on top of the software latency
in cycles, the total latency since the packet was received in hardware.
The API is used to compute a delta in the TX callback. The raw amount of
ticks is converted to cycles using a variation of the technique describe above.

Aside from offloading timestamping, which relieve the
software from a few operations, this allows to get much more precision
when studying the source of the latency in a system.
Eg. in our 100G, CX5 setup the rxtx callback application shows
SW latency is around 74 cycles (TSC is 3.2Ghz), but the latency
including NIC processing, PCIe, and queuing is around 196 cycles.

One may think at first this API is overlapping with te_eth_timesync_read_time.
rte_eth_timesync_read_time is clearly identified as part of a set of functions
to use PTP synchronization.
The device raw clock is not "sync" in any way. More importantly, the returned
value is not a timeval, but an amount of ticks. We could have a cast-based
solution, but on top of being an ugly solution, some people seeing the timeval
type of rte_eth_timesync_read_time could use it blindly.

Change in v2:
  - Rebase on current master

Change in v3:
  - Address comments from Ferruh Yigit

Tom Barbette (3):
  rte_ethdev: Add API function to read dev clock
  mlx5: Implement support for read_clock
  rxtx_callbacks: Add support for HW timestamp

 doc/guides/nics/features.rst                |  1 +
 doc/guides/sample_app_ug/rxtx_callbacks.rst |  9 ++-
 drivers/net/mlx5/mlx5.c                     |  1 +
 drivers/net/mlx5/mlx5.h                     |  1 +
 drivers/net/mlx5/mlx5_ethdev.c              | 30 +++++++
 drivers/net/mlx5/mlx5_glue.c                |  8 ++
 drivers/net/mlx5/mlx5_glue.h                |  2 +
 examples/rxtx_callbacks/Makefile            |  3 +
 examples/rxtx_callbacks/main.c              | 87 ++++++++++++++++++++-
 examples/rxtx_callbacks/meson.build         |  3 +
 lib/librte_ethdev/rte_ethdev.c              | 13 +++
 lib/librte_ethdev/rte_ethdev.h              | 45 +++++++++++
 lib/librte_ethdev/rte_ethdev_core.h         |  6 ++
 lib/librte_ethdev/rte_ethdev_version.map    |  2 +
 lib/librte_mbuf/rte_mbuf.h                  |  2 +
 15 files changed, 208 insertions(+), 5 deletions(-)

-- 
2.17.1

[dpdk-dev] [PATCH v3 1/3] rte_ethdev: Add API function to read dev clock

[Tom Barbette]

Add rte_eth_read_clock to read the raw clock of a devide.

The main use is to get the device clock conversion co-efficients to be
able to translate the raw clock of the timestamp field of the pkt mbuf
to a local synced time value.

This function was missing to allow users to convert the RX timestamp field
to real time without the complexity of the rte_timesync* facility. One can
derivate the clock frequency by calling twice read_clock and then keep a
common time base.

Signed-off-by: Tom Barbette <barbette@kth.se>
---
 doc/guides/nics/features.rst             |  1 +
 lib/librte_ethdev/rte_ethdev.c           | 13 +++++++
 lib/librte_ethdev/rte_ethdev.h           | 45 ++++++++++++++++++++++++
 lib/librte_ethdev/rte_ethdev_core.h      |  6 ++++
 lib/librte_ethdev/rte_ethdev_version.map |  2 ++
 lib/librte_mbuf/rte_mbuf.h               |  2 ++
 6 files changed, 69 insertions(+)

diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst
index c5bf32222..025b7f812 100644
--- a/doc/guides/nics/features.rst
+++ b/doc/guides/nics/features.rst
@@ -602,6 +602,7 @@ Supports Timestamp.
 * **[provides] mbuf**: ``mbuf.ol_flags:PKT_RX_TIMESTAMP``.
 * **[provides] mbuf**: ``mbuf.timestamp``.
 * **[provides] rte_eth_dev_info**: ``rx_offload_capa,rx_queue_offload_capa: DEV_RX_OFFLOAD_TIMESTAMP``.
+* **[related] eth_dev_ops**: ``read_clock``.
 
 .. _nic_features_macsec_offload:
 
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
index d7cfa3d53..22e35d839 100644
--- a/lib/librte_ethdev/rte_ethdev.c
+++ b/lib/librte_ethdev/rte_ethdev.c
@@ -4170,6 +4170,19 @@ rte_eth_timesync_write_time(uint16_t port_id, const struct timespec *timestamp)
 								timestamp));
 }
 
+int
+rte_eth_read_clock(uint16_t port_id, uint64_t *timestamp)
+{
+	struct rte_eth_dev *dev;
+
+	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
+	dev = &rte_eth_devices[port_id];
+
+	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->read_clock, -ENOTSUP);
+	return eth_err(port_id, (*dev->dev_ops->read_clock)(dev,
+								timestamp));
+}
+
 int
 rte_eth_dev_get_reg_info(uint16_t port_id, struct rte_dev_reg_info *info)
 {
diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
index b8d19c69f..dfaf16a56 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -3793,6 +3793,51 @@ int rte_eth_timesync_read_time(uint16_t port_id, struct timespec *time);
  */
 int rte_eth_timesync_write_time(uint16_t port_id, const struct timespec *time);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Read the current clock counter of an Ethernet device
+ *
+ * This returns the current raw clock value of an Ethernet device.
+ * The value returned here is from the same clock than the one
+ * filling timestamp field of RX packets. Therefore it can be used
+ * to compute a precise conversion of the device clock to the real time.
+ *
+ * E.g, a simple heuristic to derivate the frequency would be:
+ * uint64_t start, end;
+ * rte_eth_read_clock(port, start);
+ * rte_delay_ms(100);
+ * rte_eth_read_clock(port, end);
+ * double freq = (end - start) * 10;
+ *
+ * Compute a common reference with:
+ * uint64_t base_time_sec = current_time();
+ * uint64_t base_clock;
+ * rte_eth_read_clock(port, base_clock);
+ *
+ * Then, convert the raw mbuf timestamp with:
+ * base_time_sec + (double)(mbuf->timestamp - base_clock) / freq;
+ *
+ * This simple example will not provide a very good accuracy. One must
+ * at least measure multiple times the frequency and do a regression.
+ * To avoid deviation from the system time, the common reference can
+ * be repeated from time to time. The integer division can also be
+ * converted by a multiplication and a shift for better performance.
+ *
+ * @param port_id
+ *   The port identifier of the Ethernet device.
+ * @param time
+ *   Pointer to the uint64_t that holds the raw clock value.
+ *
+ * @return
+ *   - 0: Success.
+ *   - -ENODEV: The port ID is invalid.
+ *   - -ENOTSUP: The function is not supported by the Ethernet driver.
+ */
+int __rte_experimental
+rte_eth_read_clock(uint16_t port_id, uint64_t *timestamp);
+
 /**
  * Config l2 tunnel ether type of an Ethernet device for filtering specific
  * tunnel packets by ether type.
diff --git a/lib/librte_ethdev/rte_ethdev_core.h b/lib/librte_ethdev/rte_ethdev_core.h
index 8f03f83f6..86806b3eb 100644
--- a/lib/librte_ethdev/rte_ethdev_core.h
+++ b/lib/librte_ethdev/rte_ethdev_core.h
@@ -322,6 +322,10 @@ typedef int (*eth_timesync_write_time)(struct rte_eth_dev *dev,
 				       const struct timespec *timestamp);
 /**< @internal Function used to get time from the device clock */
 
+typedef int (*eth_read_clock)(struct rte_eth_dev *dev,
+				      uint64_t *timestamp);
+/**< @internal Function used to get the current value of the device clock. */
+
 typedef int (*eth_get_reg_t)(struct rte_eth_dev *dev,
 				struct rte_dev_reg_info *info);
 /**< @internal Retrieve registers  */
@@ -496,6 +500,8 @@ struct eth_dev_ops {
 	eth_timesync_read_time     timesync_read_time; /** Get the device clock time. */
 	eth_timesync_write_time    timesync_write_time; /** Set the device clock time. */
 
+	eth_read_clock             read_clock;
+
 	eth_xstats_get_by_id_t     xstats_get_by_id;
 	/**< Get extended device statistic values by ID. */
 	eth_xstats_get_names_by_id_t xstats_get_names_by_id;
diff --git a/lib/librte_ethdev/rte_ethdev_version.map b/lib/librte_ethdev/rte_ethdev_version.map
index afcd25599..670e4fad5 100644
--- a/lib/librte_ethdev/rte_ethdev_version.map
+++ b/lib/librte_ethdev/rte_ethdev_version.map
@@ -253,10 +253,12 @@ EXPERIMENTAL {
 	rte_eth_dev_rx_intr_ctl_q_get_fd;
 	rte_eth_find_next_of;
 	rte_eth_find_next_sibling;
+	rte_eth_read_clock;
 	rte_eth_switch_domain_alloc;
 	rte_eth_switch_domain_free;
 	rte_flow_conv;
 	rte_flow_expand_rss;
+	rte_eth_read_clock;
 	rte_mtr_capabilities_get;
 	rte_mtr_create;
 	rte_mtr_destroy;
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 68415af02..e530a96c5 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -668,6 +668,8 @@ struct rte_mbuf {
 
 	/** Valid if PKT_RX_TIMESTAMP is set. The unit and time reference
 	 * are not normalized but are always the same for a given port.
+	 * Some devices allow to query rte_eth_read_clock that will return the
+	 * current device timestamp.
 	 */
 	uint64_t timestamp;
 
-- 
2.17.1

[dpdk-dev] [PATCH v3 2/3] mlx5: Implement support for read_clock

[Tom Barbette]

Implements support for read_clock for the mlx5 driver. mlx5 supports
hardware timestamp offload, setting packets timestamp field to the
device clock. rte_eth_read_clock allows to read the device's current
clock value and therefore compare values on similar time base.

See rxtx_callbacks for an example.

Signed-off-by: Tom Barbette <barbette@kth.se>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>
---
 drivers/net/mlx5/mlx5.c        |  1 +
 drivers/net/mlx5/mlx5.h        |  1 +
 drivers/net/mlx5/mlx5_ethdev.c | 30 ++++++++++++++++++++++++++++++
 drivers/net/mlx5/mlx5_glue.c   |  8 ++++++++
 drivers/net/mlx5/mlx5_glue.h   |  2 ++
 5 files changed, 42 insertions(+)

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 46ca08a4d..947943346 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -748,6 +748,7 @@ const struct eth_dev_ops mlx5_dev_ops = {
 	.xstats_get_names = mlx5_xstats_get_names,
 	.fw_version_get = mlx5_fw_version_get,
 	.dev_infos_get = mlx5_dev_infos_get,
+	.read_clock = mlx5_read_clock,
 	.dev_supported_ptypes_get = mlx5_dev_supported_ptypes_get,
 	.vlan_filter_set = mlx5_vlan_filter_set,
 	.rx_queue_setup = mlx5_rx_queue_setup,
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index 0a6d7f1d5..9602001ce 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -403,6 +403,7 @@ int mlx5_set_flags(struct rte_eth_dev *dev, unsigned int keep,
 		   unsigned int flags);
 int mlx5_dev_configure(struct rte_eth_dev *dev);
 void mlx5_dev_infos_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *info);
+int mlx5_read_clock(struct rte_eth_dev *dev, uint64_t *time);
 int mlx5_fw_version_get(struct rte_eth_dev *dev, char *fw_ver, size_t fw_size);
 const uint32_t *mlx5_dev_supported_ptypes_get(struct rte_eth_dev *dev);
 int mlx5_link_update(struct rte_eth_dev *dev, int wait_to_complete);
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 57a64495d..00906f99d 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -564,6 +564,36 @@ mlx5_dev_infos_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *info)
 	}
 }
 
+/**
+ * Get device current raw clock counter
+ *
+ * @param dev
+ *   Pointer to Ethernet device structure.
+ * @param[out] time
+ *   Current raw clock counter of the device.
+ *
+ * @return
+ *   0 if the clock has correctly been read
+ *   The value of errno in case of error
+ */
+int
+mlx5_read_clock(struct rte_eth_dev *dev, uint64_t *clock)
+{
+	struct mlx5_priv *priv = dev->data->dev_private;
+	struct ibv_context *ctx = priv->sh->ctx;
+	struct ibv_values_ex values;
+	int err = 0;
+
+	values.comp_mask = IBV_VALUES_MASK_RAW_CLOCK;
+	err = mlx5_glue->query_rt_values_ex(ctx, &values);
+	if (err != 0) {
+		DRV_LOG(WARNING, "Could not query the clock !");
+		return err;
+	}
+	*clock = values.raw_clock.tv_nsec;
+	return 0;
+}
+
 /**
  * Get firmware version of a device.
  *
diff --git a/drivers/net/mlx5/mlx5_glue.c b/drivers/net/mlx5/mlx5_glue.c
index b32cd09c3..c1c650cff 100644
--- a/drivers/net/mlx5/mlx5_glue.c
+++ b/drivers/net/mlx5/mlx5_glue.c
@@ -87,6 +87,13 @@ mlx5_glue_query_device_ex(struct ibv_context *context,
 	return ibv_query_device_ex(context, input, attr);
 }
 
+static int
+mlx5_glue_query_rt_values_ex(struct ibv_context *context,
+			  struct ibv_values_ex *values)
+{
+	return ibv_query_rt_values_ex(context, values);
+}
+
 static int
 mlx5_glue_query_port(struct ibv_context *context, uint8_t port_num,
 		     struct ibv_port_attr *port_attr)
@@ -834,6 +841,7 @@ const struct mlx5_glue *mlx5_glue = &(const struct mlx5_glue){
 	.close_device = mlx5_glue_close_device,
 	.query_device = mlx5_glue_query_device,
 	.query_device_ex = mlx5_glue_query_device_ex,
+	.query_rt_values_ex = mlx5_glue_query_rt_values_ex,
 	.query_port = mlx5_glue_query_port,
 	.create_comp_channel = mlx5_glue_create_comp_channel,
 	.destroy_comp_channel = mlx5_glue_destroy_comp_channel,
diff --git a/drivers/net/mlx5/mlx5_glue.h b/drivers/net/mlx5/mlx5_glue.h
index 1d06583f4..e76e0b7af 100644
--- a/drivers/net/mlx5/mlx5_glue.h
+++ b/drivers/net/mlx5/mlx5_glue.h
@@ -83,6 +83,8 @@ struct mlx5_glue {
 	int (*query_device_ex)(struct ibv_context *context,
 			       const struct ibv_query_device_ex_input *input,
 			       struct ibv_device_attr_ex *attr);
+	int (*query_rt_values_ex)(struct ibv_context *context,
+			       struct ibv_values_ex *values);
 	int (*query_port)(struct ibv_context *context, uint8_t port_num,
 			  struct ibv_port_attr *port_attr);
 	struct ibv_comp_channel *(*create_comp_channel)
-- 
2.17.1

[dpdk-dev] [PATCH v3 3/3] rxtx_callbacks: Add support for HW timestamp

[Tom Barbette]

Use rxtx callback to demonstrate a way to use rte_eth_read_clock to
convert the hardware timestamps to an amount of cycles.

This allows to get the amount of time the packet spent since its entry
in the device. While the regular latency only shows the latency from
when it entered the software stack.

Signed-off-by: Tom Barbette <barbette@kth.se>
---
 doc/guides/sample_app_ug/rxtx_callbacks.rst |  9 ++-
 examples/rxtx_callbacks/Makefile            |  3 +
 examples/rxtx_callbacks/main.c              | 87 ++++++++++++++++++++-
 examples/rxtx_callbacks/meson.build         |  3 +
 4 files changed, 97 insertions(+), 5 deletions(-)

diff --git a/doc/guides/sample_app_ug/rxtx_callbacks.rst b/doc/guides/sample_app_ug/rxtx_callbacks.rst
index 81463d28d..6b0c64461 100644
--- a/doc/guides/sample_app_ug/rxtx_callbacks.rst
+++ b/doc/guides/sample_app_ug/rxtx_callbacks.rst
@@ -13,6 +13,10 @@ In the sample application a user defined callback is applied to all received
 packets to add a timestamp. A separate callback is applied to all packets
 prior to transmission to calculate the elapsed time, in CPU cycles.
 
+If hardware timestamping is supported by the NIC, the sample application will
+also display the average latency since the packet was timestamped in hardware,
+on top of the latency since the packet was received and processed by the RX
+callback.
 
 Compiling the Application
 -------------------------
@@ -36,7 +40,10 @@ To run the example in a ``linux`` environment:
 
 .. code-block:: console
 
-    ./build/rxtx_callbacks -l 1 -n 4
+    ./build/rxtx_callbacks -l 1 -n 4 -- [-t]
+
+Use -t to enable hardware timestamping. If not supported by the NIC, an error
+will be displayed.
 
 Refer to *DPDK Getting Started Guide* for general information on running
 applications and the Environment Abstraction Layer (EAL) options.
diff --git a/examples/rxtx_callbacks/Makefile b/examples/rxtx_callbacks/Makefile
index b937d599b..0a4660681 100644
--- a/examples/rxtx_callbacks/Makefile
+++ b/examples/rxtx_callbacks/Makefile
@@ -50,6 +50,9 @@ include $(RTE_SDK)/mk/rte.vars.mk
 
 CFLAGS += $(WERROR_FLAGS)
 
+# rte_eth_read_clock is experimental
+CFLAGS += -DALLOW_EXPERIMENTAL_API
+
 # workaround for a gcc bug with noreturn attribute
 # http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12603
 ifeq ($(CONFIG_RTE_TOOLCHAIN_GCC),y)
diff --git a/examples/rxtx_callbacks/main.c b/examples/rxtx_callbacks/main.c
index 2058be627..55aa82288 100644
--- a/examples/rxtx_callbacks/main.c
+++ b/examples/rxtx_callbacks/main.c
@@ -4,6 +4,7 @@
 
 #include <stdint.h>
 #include <inttypes.h>
+#include <getopt.h>
 #include <rte_eal.h>
 #include <rte_ethdev.h>
 #include <rte_cycles.h>
@@ -17,6 +18,9 @@
 #define MBUF_CACHE_SIZE 250
 #define BURST_SIZE 32
 
+static const char usage[] =
+	"%s EAL_ARGS -- [-t]\n";
+
 static const struct rte_eth_conf port_conf_default = {
 	.rxmode = {
 		.max_rx_pkt_len = ETHER_MAX_LEN,
@@ -25,9 +29,14 @@ static const struct rte_eth_conf port_conf_default = {
 
 static struct {
 	uint64_t total_cycles;
+	uint64_t total_queue_cycles;
 	uint64_t total_pkts;
 } latency_numbers;
 
+int hw_timestamping;
+
+#define TICKS_PER_CYCLE_SHIFT 16
+static uint64_t ticks_per_cycle_mult;
 
 static uint16_t
 add_timestamps(uint16_t port __rte_unused, uint16_t qidx __rte_unused,
@@ -43,22 +52,42 @@ add_timestamps(uint16_t port __rte_unused, uint16_t qidx __rte_unused,
 }
 
 static uint16_t
-calc_latency(uint16_t port __rte_unused, uint16_t qidx __rte_unused,
+calc_latency(uint16_t port, uint16_t qidx __rte_unused,
 		struct rte_mbuf **pkts, uint16_t nb_pkts, void *_ __rte_unused)
 {
 	uint64_t cycles = 0;
+	uint64_t queue_ticks = 0;
 	uint64_t now = rte_rdtsc();
+	uint64_t ticks;
 	unsigned i;
 
-	for (i = 0; i < nb_pkts; i++)
+	if (hw_timestamping)
+		rte_eth_read_clock(port, &ticks);
+
+	for (i = 0; i < nb_pkts; i++) {
 		cycles += now - pkts[i]->udata64;
+		if (hw_timestamping)
+			queue_ticks += ticks - pkts[i]->timestamp;
+	}
+
 	latency_numbers.total_cycles += cycles;
+	if (hw_timestamping)
+		latency_numbers.total_queue_cycles += (queue_ticks
+			* ticks_per_cycle_mult) >> TICKS_PER_CYCLE_SHIFT;
+
 	latency_numbers.total_pkts += nb_pkts;
 
 	if (latency_numbers.total_pkts > (100 * 1000 * 1000ULL)) {
 		printf("Latency = %"PRIu64" cycles\n",
 		latency_numbers.total_cycles / latency_numbers.total_pkts);
-		latency_numbers.total_cycles = latency_numbers.total_pkts = 0;
+		if (hw_timestamping) {
+			printf("Latency from HW = %"PRIu64" cycles\n",
+			   latency_numbers.total_queue_cycles
+			   / latency_numbers.total_pkts);
+		}
+		latency_numbers.total_cycles = 0;
+		latency_numbers.total_queue_cycles = 0;
+		latency_numbers.total_pkts = 0;
 	}
 	return nb_pkts;
 }
@@ -77,6 +106,7 @@ port_init(uint16_t port, struct rte_mempool *mbuf_pool)
 	int retval;
 	uint16_t q;
 	struct rte_eth_dev_info dev_info;
+	struct rte_eth_rxconf rxconf;
 	struct rte_eth_txconf txconf;
 
 	if (!rte_eth_dev_is_valid_port(port))
@@ -95,9 +125,20 @@ port_init(uint16_t port, struct rte_mempool *mbuf_pool)
 	if (retval != 0)
 		return retval;
 
+	rxconf = dev_info.default_rxconf;
+
+	if (hw_timestamping) {
+		if (!(dev_info.rx_offload_capa & DEV_RX_OFFLOAD_TIMESTAMP)) {
+			printf("\nERROR: Port %u does not support hardware timestamping\n"
+					, port);
+			return -1;
+		}
+		rxconf.offloads |= DEV_RX_OFFLOAD_TIMESTAMP;
+	}
+
 	for (q = 0; q < rx_rings; q++) {
 		retval = rte_eth_rx_queue_setup(port, q, nb_rxd,
-				rte_eth_dev_socket_id(port), NULL, mbuf_pool);
+			rte_eth_dev_socket_id(port), &rxconf, mbuf_pool);
 		if (retval < 0)
 			return retval;
 	}
@@ -115,6 +156,27 @@ port_init(uint16_t port, struct rte_mempool *mbuf_pool)
 	if (retval < 0)
 		return retval;
 
+	if (hw_timestamping && ticks_per_cycle_mult  == 0) {
+		uint64_t cycles_base = rte_rdtsc();
+		uint64_t ticks_base;
+		retval = rte_eth_read_clock(port, &ticks_base);
+		if (retval != 0)
+			return retval;
+		rte_delay_ms(100);
+		uint64_t cycles = rte_rdtsc();
+		uint64_t ticks;
+		rte_eth_read_clock(port, &ticks);
+		uint64_t c_freq = cycles - cycles_base;
+		uint64_t t_freq = ticks - ticks_base;
+		double freq_mult = (double)c_freq / t_freq;
+		printf("TSC Freq ~= %lu\nHW Freq ~= %lu\nRatio : %f\n",
+				c_freq * 10, t_freq * 10, freq_mult);
+		/* TSC will be faster than internal ticks so freq_mult is > 0
+		 * We convert the multiplication to an integer shift & mult
+		 */
+		ticks_per_cycle_mult = (1 << TICKS_PER_CYCLE_SHIFT) / freq_mult;
+	}
+
 	struct ether_addr addr;
 
 	rte_eth_macaddr_get(port, &addr);
@@ -177,6 +239,11 @@ main(int argc, char *argv[])
 	struct rte_mempool *mbuf_pool;
 	uint16_t nb_ports;
 	uint16_t portid;
+	struct option lgopts[] = {
+		{ NULL,  0, 0, 0 }
+	};
+	int opt, option_index;
+
 
 	/* init EAL */
 	int ret = rte_eal_init(argc, argv);
@@ -186,6 +253,18 @@ main(int argc, char *argv[])
 	argc -= ret;
 	argv += ret;
 
+	while ((opt = getopt_long(argc, argv, "t", lgopts, &option_index))
+			!= EOF)
+		switch (opt) {
+		case 't':
+			hw_timestamping = 1;
+			break;
+		default:
+			printf(usage, argv[0]);
+			return -1;
+		}
+	optind = 1; /* reset getopt lib */
+
 	nb_ports = rte_eth_dev_count_avail();
 	if (nb_ports < 2 || (nb_ports & 1))
 		rte_exit(EXIT_FAILURE, "Error: number of ports must be even\n");
diff --git a/examples/rxtx_callbacks/meson.build b/examples/rxtx_callbacks/meson.build
index c34e11e36..a7bf12dd3 100644
--- a/examples/rxtx_callbacks/meson.build
+++ b/examples/rxtx_callbacks/meson.build
@@ -6,6 +6,9 @@
 # To build this example as a standalone application with an already-installed
 # DPDK instance, use 'make'
 
+#rte_eth_read_clock is experimental
+allow_experimental_apis = true
+
 sources = files(
 	'main.c'
 )
-- 
2.17.1

Re: [dpdk-dev] [PATCH v3 1/3] rte_ethdev: Add API function to read dev clock

[Andrew Rybchenko]

On 4/24/19 8:34 PM, Tom Barbette wrote:
> Add rte_eth_read_clock to read the raw clock of a devide.

Typo above "devide"

> The main use is to get the device clock conversion co-efficients to be
> able to translate the raw clock of the timestamp field of the pkt mbuf
> to a local synced time value.
>
> This function was missing to allow users to convert the RX timestamp field

RX -> Rx

> to real time without the complexity of the rte_timesync* facility. One can
> derivate the clock frequency by calling twice read_clock and then keep a
> common time base.
>
> Signed-off-by: Tom Barbette <barbette@kth.se>

[snip]

> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index d7cfa3d53..22e35d839 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -4170,6 +4170,19 @@ rte_eth_timesync_write_time(uint16_t port_id, const struct timespec *timestamp)
>   								timestamp));
>   }
>   
> +int
> +rte_eth_read_clock(uint16_t port_id, uint64_t *timestamp)
> +{
> +	struct rte_eth_dev *dev;
> +
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	dev = &rte_eth_devices[port_id];
> +
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->read_clock, -ENOTSUP);
> +	return eth_err(port_id, (*dev->dev_ops->read_clock)(dev,
> +								timestamp));

Why timestamp on the next line?

> +}
> +
>   int
>   rte_eth_dev_get_reg_info(uint16_t port_id, struct rte_dev_reg_info *info)
>   {
> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> index b8d19c69f..dfaf16a56 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -3793,6 +3793,51 @@ int rte_eth_timesync_read_time(uint16_t port_id, struct timespec *time);
>    */
>   int rte_eth_timesync_write_time(uint16_t port_id, const struct timespec *time);
>   
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Read the current clock counter of an Ethernet device
> + *
> + * This returns the current raw clock value of an Ethernet device.
> + * The value returned here is from the same clock than the one
> + * filling timestamp field of RX packets. Therefore it can be used

RX -> Rx

> + * to compute a precise conversion of the device clock to the real time.
> + *
> + * E.g, a simple heuristic to derivate the frequency would be:
> + * uint64_t start, end;
> + * rte_eth_read_clock(port, start);
> + * rte_delay_ms(100);
> + * rte_eth_read_clock(port, end);
> + * double freq = (end - start) * 10;
> + *
> + * Compute a common reference with:
> + * uint64_t base_time_sec = current_time();
> + * uint64_t base_clock;
> + * rte_eth_read_clock(port, base_clock);
> + *
> + * Then, convert the raw mbuf timestamp with:
> + * base_time_sec + (double)(mbuf->timestamp - base_clock) / freq;
> + *
> + * This simple example will not provide a very good accuracy. One must
> + * at least measure multiple times the frequency and do a regression.
> + * To avoid deviation from the system time, the common reference can
> + * be repeated from time to time. The integer division can also be
> + * converted by a multiplication and a shift for better performance.
> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param time
> + *   Pointer to the uint64_t that holds the raw clock value.
> + *
> + * @return
> + *   - 0: Success.
> + *   - -ENODEV: The port ID is invalid.
> + *   - -ENOTSUP: The function is not supported by the Ethernet driver.
> + */
> +int __rte_experimental
> +rte_eth_read_clock(uint16_t port_id, uint64_t *timestamp);
> +
>   /**
>    * Config l2 tunnel ether type of an Ethernet device for filtering specific
>    * tunnel packets by ether type.

[snip]

> eth_xstats_get_names_by_id_t xstats_get_names_by_id;
> diff --git a/lib/librte_ethdev/rte_ethdev_version.map b/lib/librte_ethdev/rte_ethdev_version.map
> index afcd25599..670e4fad5 100644
> --- a/lib/librte_ethdev/rte_ethdev_version.map
> +++ b/lib/librte_ethdev/rte_ethdev_version.map
> @@ -253,10 +253,12 @@ EXPERIMENTAL {
>   	rte_eth_dev_rx_intr_ctl_q_get_fd;
>   	rte_eth_find_next_of;
>   	rte_eth_find_next_sibling;
> +	rte_eth_read_clock;
>   	rte_eth_switch_domain_alloc;
>   	rte_eth_switch_domain_free;
>   	rte_flow_conv;
>   	rte_flow_expand_rss;
> +	rte_eth_read_clock;

Dup

[snip]

Re: [dpdk-dev] [PATCH v3 1/3] rte_ethdev: Add API function to read dev clock

[Wiles, Keith]

> On Apr 24, 2019, at 12:34 PM, Tom Barbette <barbette@kth.se> wrote:
> 
> Add rte_eth_read_clock to read the raw clock of a devide.
> 
> The main use is to get the device clock conversion co-efficients to be
> able to translate the raw clock of the timestamp field of the pkt mbuf
> to a local synced time value.
> 
> This function was missing to allow users to convert the RX timestamp field
> to real time without the complexity of the rte_timesync* facility. One can
> derivate the clock frequency by calling twice read_clock and then keep a
> common time base.
> 
> Signed-off-by: Tom Barbette <barbette@kth.se>
> ---
> doc/guides/nics/features.rst             |  1 +
> lib/librte_ethdev/rte_ethdev.c           | 13 +++++++
> lib/librte_ethdev/rte_ethdev.h           | 45 ++++++++++++++++++++++++
> lib/librte_ethdev/rte_ethdev_core.h      |  6 ++++
> lib/librte_ethdev/rte_ethdev_version.map |  2 ++
> lib/librte_mbuf/rte_mbuf.h               |  2 ++
> 6 files changed, 69 insertions(+)
> 
> diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst
> index c5bf32222..025b7f812 100644
> --- a/doc/guides/nics/features.rst
> +++ b/doc/guides/nics/features.rst
> @@ -602,6 +602,7 @@ Supports Timestamp.
> * **[provides] mbuf**: ``mbuf.ol_flags:PKT_RX_TIMESTAMP``.
> * **[provides] mbuf**: ``mbuf.timestamp``.
> * **[provides] rte_eth_dev_info**: ``rx_offload_capa,rx_queue_offload_capa: DEV_RX_OFFLOAD_TIMESTAMP``.
> +* **[related] eth_dev_ops**: ``read_clock``.
> 
> .. _nic_features_macsec_offload:
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index d7cfa3d53..22e35d839 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -4170,6 +4170,19 @@ rte_eth_timesync_write_time(uint16_t port_id, const struct timespec *timestamp)
> 								timestamp));
> }
> 
> +int
> +rte_eth_read_clock(uint16_t port_id, uint64_t *timestamp)
> +{
> +	struct rte_eth_dev *dev;
> +
> +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> +	dev = &rte_eth_devices[port_id];
> +
> +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->read_clock, -ENOTSUP);
> +	return eth_err(port_id, (*dev->dev_ops->read_clock)(dev,
> +								timestamp));
> +}
> +
> int
> rte_eth_dev_get_reg_info(uint16_t port_id, struct rte_dev_reg_info *info)
> {
> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
> index b8d19c69f..dfaf16a56 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -3793,6 +3793,51 @@ int rte_eth_timesync_read_time(uint16_t port_id, struct timespec *time);
>  */
> int rte_eth_timesync_write_time(uint16_t port_id, const struct timespec *time);
> 
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Read the current clock counter of an Ethernet device
> + *
> + * This returns the current raw clock value of an Ethernet device.
> + * The value returned here is from the same clock than the one
> + * filling timestamp field of RX packets. Therefore it can be used
> + * to compute a precise conversion of the device clock to the real time.
> + *
> + * E.g, a simple heuristic to derivate the frequency would be:
> + * uint64_t start, end;
> + * rte_eth_read_clock(port, start);
> + * rte_delay_ms(100);
> + * rte_eth_read_clock(port, end);
> + * double freq = (end - start) * 10;
> + *
> + * Compute a common reference with:
> + * uint64_t base_time_sec = current_time();
> + * uint64_t base_clock;
> + * rte_eth_read_clock(port, base_clock);
> + *
> + * Then, convert the raw mbuf timestamp with:
> + * base_time_sec + (double)(mbuf->timestamp - base_clock) / freq;
> + *
> + * This simple example will not provide a very good accuracy. One must
> + * at least measure multiple times the frequency and do a regression.
> + * To avoid deviation from the system time, the common reference can
> + * be repeated from time to time. The integer division can also be
> + * converted by a multiplication and a shift for better performance.
> + *
> + * @param port_id
> + *   The port identifier of the Ethernet device.
> + * @param time
> + *   Pointer to the uint64_t that holds the raw clock value.

What is a raw clock value? It took me a bit to find that it is in nano-seconds need to document that point.
> + *
> + * @return
> + *   - 0: Success.
> + *   - -ENODEV: The port ID is invalid.
> + *   - -ENOTSUP: The function is not supported by the Ethernet driver.
> + */
> +int __rte_experimental
> +rte_eth_read_clock(uint16_t port_id, uint64_t *timestamp);

Using timestamp variable is not very descriptive and some other name needs to be used. Also in the driver it is called *clock.

Another question is why does this routine not perform the looping/delaying and calling read_clock and then return frequency instead. If you want a timestamp reading function then this one is not being described that way and I would think it should be done someplace else or should be.
> +
> /**
>  * Config l2 tunnel ether type of an Ethernet device for filtering specific
>  * tunnel packets by ether type.
> diff --git a/lib/librte_ethdev/rte_ethdev_core.h b/lib/librte_ethdev/rte_ethdev_core.h
> index 8f03f83f6..86806b3eb 100644
> --- a/lib/librte_ethdev/rte_ethdev_core.h
> +++ b/lib/librte_ethdev/rte_ethdev_core.h
> @@ -322,6 +322,10 @@ typedef int (*eth_timesync_write_time)(struct rte_eth_dev *dev,
> 				       const struct timespec *timestamp);
> /**< @internal Function used to get time from the device clock */
> 
> +typedef int (*eth_read_clock)(struct rte_eth_dev *dev,
> +				      uint64_t *timestamp);
> +/**< @internal Function used to get the current value of the device clock. */
> +
> typedef int (*eth_get_reg_t)(struct rte_eth_dev *dev,
> 				struct rte_dev_reg_info *info);
> /**< @internal Retrieve registers  */
> @@ -496,6 +500,8 @@ struct eth_dev_ops {
> 	eth_timesync_read_time     timesync_read_time; /** Get the device clock time. */
> 	eth_timesync_write_time    timesync_write_time; /** Set the device clock time. */
> 
> +	eth_read_clock             read_clock;
> +
> 	eth_xstats_get_by_id_t     xstats_get_by_id;
> 	/**< Get extended device statistic values by ID. */
> 	eth_xstats_get_names_by_id_t xstats_get_names_by_id;
> diff --git a/lib/librte_ethdev/rte_ethdev_version.map b/lib/librte_ethdev/rte_ethdev_version.map
> index afcd25599..670e4fad5 100644
> --- a/lib/librte_ethdev/rte_ethdev_version.map
> +++ b/lib/librte_ethdev/rte_ethdev_version.map
> @@ -253,10 +253,12 @@ EXPERIMENTAL {
> 	rte_eth_dev_rx_intr_ctl_q_get_fd;
> 	rte_eth_find_next_of;
> 	rte_eth_find_next_sibling;
> +	rte_eth_read_clock;
> 	rte_eth_switch_domain_alloc;
> 	rte_eth_switch_domain_free;
> 	rte_flow_conv;
> 	rte_flow_expand_rss;
> +	rte_eth_read_clock;
> 	rte_mtr_capabilities_get;
> 	rte_mtr_create;
> 	rte_mtr_destroy;
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 68415af02..e530a96c5 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -668,6 +668,8 @@ struct rte_mbuf {
> 
> 	/** Valid if PKT_RX_TIMESTAMP is set. The unit and time reference
> 	 * are not normalized but are always the same for a given port.
> +	 * Some devices allow to query rte_eth_read_clock that will return the
> +	 * current device timestamp.

The message here is not a good place for this detail, I would put it in the function call doc above.
> 	 */
> 	uint64_t timestamp;
> 
> -- 
> 2.17.1
> 

Regards,
Keith

Re: [dpdk-dev] [PATCH v3 1/3] rte_ethdev: Add API function to read dev clock

[Tom Barbette]

@Andrew I applied your comments. Thanks.

On 2019-04-25 20:28, Wiles, Keith wrote:
> What is a raw clock value? It took me a bit to find that it is in nano-seconds need to document that point.

It is not in nanosecond, it has no units. Finding the relation between 
the device clock and the real time is the whole point of this API.

> Using timestamp variable is not very descriptive and some other name needs to be used. Also in the driver it is called *clock.

The problem is that the "timestamp offload" feature filling the 
timestamp field of the pktmbuf is already badly named as it is given 
without time unit. Both of them are not timestamp but raw "clock" 
values, a number of ticks at an unknown frequency, with an unknow time 
base (ie is it the number of ticks since boot? Device is up? 1/1/1970?).
One solution would be to have an union in the pktmbuf, changing the 
timestamp field into a "clock" or "timestamp" field. But it's a bit 
overkill.

I propose to change the read_clock API to reference "clock" instead of 
timestamp everywhere.

> Another question is why does this routine not perform the looping/delaying and calling read_clock and then return frequency instead. If you want a timestamp reading function then this one is not being described that way and I would think it should be done someplace else or should be.

The frequency is one thing, and would allow to give a relative time in 
second between packets. In practice though, we change the frequency (as 
Linux does regarding the TSC ticks) to catch up corrections applied by 
NTP on the source clock.
The second thing is the time reference, to convert the clock time (of 
the packets) to the current wall time. One may want to use the monotonic 
clock, the real clock (we do follow both). Or no system clock at all and 
directly follow an NTP source. The point is, having a function to give 
the frequency is not enough. One can derive the frequency and the time 
reference with this API. I could write a helper in a second step to get 
the frequency out of read_clock. But the time reference implies timers, 
choosing a source, and stuff we don't want here, I think...

>> 	/** Valid if PKT_RX_TIMESTAMP is set. The unit and time reference
>> 	 * are not normalized but are always the same for a given port.
>> +	 * Some devices allow to query rte_eth_read_clock that will return the
>> +	 * current device timestamp.
> 
> The message here is not a good place for this detail, I would put it in the function call doc above.

I can remove these lines, but with read_clock referencing only clock I 
feel like it's even more needed. Someone reading the doc will see "oh, I 
can use timestamp offloading to get precise timing of when my packets 
were received, great ! But it has no unit and no reference... What do I 
do with that?". It miss the last step "how I see... I can look at 
rte_eth_read_clock documentation to read more about conversion."

Thanks !

Tom