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From: Shahaf Shuler <shahafs@mellanox.com>
To: Tom Barbette <barbette@kth.se>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "bruce.richardson@intel.com" <bruce.richardson@intel.com>,
	"john.mcnamara@intel.com" <john.mcnamara@intel.com>,
	Thomas Monjalon <thomas@monjalon.net>,
	Ferruh Yigit <ferruh.yigit@intel.com>,
	Andrew Rybchenko <arybchenko@solarflare.com>,
	Yongseok Koh <yskoh@mellanox.com>
Subject: Re: [dpdk-dev] [PATCH 1/3] rte_ethdev: Add API function to read dev clock
Date: Thu, 20 Dec 2018 06:42:47 +0000	[thread overview]
Message-ID: <DB7PR05MB44264497B57EF9232E7F4A69C3BF0@DB7PR05MB4426.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <20181219134934.24693-2-barbette@kth.se>

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 <barbette@kth.se>

Acked-by: Shahaf Shuler <shahafs@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

  reply	other threads:[~2018-12-20  6:42 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-19 13:49 [dpdk-dev] [PATCH 0/3] Add rte_eth_read_clock API Tom Barbette
2018-12-19 13:49 ` [dpdk-dev] [PATCH 1/3] rte_ethdev: Add API function to read dev clock Tom Barbette
2018-12-20  6:42   ` Shahaf Shuler [this message]
2018-12-20 19:55   ` Ferruh Yigit
2018-12-19 13:49 ` [dpdk-dev] [PATCH 2/3] mlx5: Implement support for read_clock Tom Barbette
2018-12-20  6:46   ` Shahaf Shuler
2018-12-19 13:49 ` [dpdk-dev] [PATCH 3/3] rxtx_callbacks: Add support for HW timestamp Tom Barbette
2018-12-21  8:25 [dpdk-dev] [PATCH 1/3] rte_ethdev: Add API function to read dev clock Tom Barbette
2018-12-23  6:06 ` Shahaf Shuler
2019-01-02 17:44   ` Ferruh Yigit
2019-01-08 11:30     ` Tom Barbette
2019-03-19 13:32       ` Yigit, Ferruh
2019-03-19 13:32         ` Yigit, Ferruh
2019-03-20 14:48         ` Thomas Monjalon
2019-03-20 14:48           ` Thomas Monjalon
2019-03-20 15:57           ` Andrew Rybchenko
2019-03-20 15:57             ` Andrew Rybchenko
2019-03-21 19:37             ` Ferruh Yigit
2019-03-21 19:37               ` Ferruh Yigit

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