Wednesday, December 19, 2018 3:50 PM, Tom Barbette:
> Subject: [PATCH 1/3] rte_ethdev: Add API function to read dev clock
>
> 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 <barbe...@kth.se>
Acked-by: Shahaf Shuler <shah...@mellanox.com>
> ---
> doc/guides/nics/features.rst | 1 +
> lib/librte_ethdev/rte_ethdev.c | 13 +++++++
> lib/librte_ethdev/rte_ethdev.h | 44 ++++++++++++++++++++++++
> lib/librte_ethdev/rte_ethdev_core.h | 6 ++++
> lib/librte_ethdev/rte_ethdev_version.map | 1 +
> lib/librte_mbuf/rte_mbuf.h | 2 ++
> 6 files changed, 67 insertions(+)
>
> diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst index
> d3f904839..45484a30f 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``.
> +* **[implements] 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 9d5107dce..97f92d11a 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -4124,6 +4124,19 @@ 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 1960f3a2d..5a831db29 100644
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> @@ -3642,6 +3642,50 @@ 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
> +*time);
> +
> /**
> * 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 92ac3de25..12d6c3c1d 100644
> --- a/lib/librte_ethdev/rte_ethdev_version.map
> +++ b/lib/librte_ethdev/rte_ethdev_version.map
> @@ -249,6 +249,7 @@ EXPERIMENTAL {
> 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
> 3dbc6695e..4ceefa913 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -605,6 +605,8 @@ 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
