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 <barbe...@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]
