From: Andrew Rybchenko <arybchenko@solarflare.com>
To: Tom Barbette <barbette@kth.se>, <dev@dpdk.org>
Cc: <bruce.richardson@intel.com>, <john.mcnamara@intel.com>,
Thomas Monjalon <thomas@monjalon.net>,
Ferruh Yigit <ferruh.yigit@intel.com>,
Shahaf Shuler <shahafs@mellanox.com>,
Yongseok Koh <yskoh@mellanox.com>, <olivier.matz@6wind.com>
Subject: Re: [dpdk-dev] [PATCH v3 1/3] rte_ethdev: Add API function to read dev clock
Date: Thu, 25 Apr 2019 20:08:07 +0300 [thread overview]
Message-ID: <735cce4a-7fe7-73fb-c4f3-1fd0daa2ef7c@solarflare.com> (raw)
In-Reply-To: <20190424173424.34628-2-barbette@kth.se>
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]
next prev parent reply other threads:[~2019-04-25 17:08 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 17:34 [dpdk-dev] [PATCH v3 0/3] Add rte_eth_read_clock API Tom Barbette
2019-04-24 17:34 ` Tom Barbette
2019-04-24 17:34 ` [dpdk-dev] [PATCH v3 1/3] rte_ethdev: Add API function to read dev clock Tom Barbette
2019-04-24 17:34 ` Tom Barbette
2019-04-25 17:08 ` Andrew Rybchenko [this message]
2019-04-25 17:08 ` Andrew Rybchenko
2019-04-25 18:28 ` Wiles, Keith
2019-04-25 18:28 ` Wiles, Keith
2019-04-26 8:13 ` Tom Barbette
2019-04-26 8:13 ` Tom Barbette
2019-04-24 17:34 ` [dpdk-dev] [PATCH v3 2/3] mlx5: Implement support for read_clock Tom Barbette
2019-04-24 17:34 ` Tom Barbette
2019-04-24 17:34 ` [dpdk-dev] [PATCH v3 3/3] rxtx_callbacks: Add support for HW timestamp Tom Barbette
2019-04-24 17:34 ` Tom Barbette
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