Lines Matching +full:rx +full:- +full:sample +full:- +full:delay +full:- +full:ns
1 .. SPDX-License-Identifier: GPL-2.0
32 IP_MULTICAST_LOOP + SO_TIMESTAMP[NS]
43 -------------------------------------------------------------
59 -------------------------------------------------------------------
62 Its struct timespec allows for higher resolution (ns) timestamps than the
72 ----------------------------------------------------------------------
102 Request rx timestamps generated by the network adapter.
105 Request rx timestamps when data enters the kernel. These timestamps
122 transmit latency is, if long, often dominated by queuing delay. The
131 grained measurement of queuing delay. This flag can be enabled
138 over-report measurement, because the timestamp is generated when all
180 is derived from a per-socket u32 counter (that wraps). For datagram
227 received the packet and its length at layer 2. A valid (non-zero)
255 Using this feature, applications can sample timestamps per sendmsg()
262 cmsg->cmsg_level = SOL_SOCKET;
263 cmsg->cmsg_type = SO_TIMESTAMPING;
264 cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
282 -------------------------
292 correlating a timestamp with data is non-trivial. A range of bytes
321 relevant sequence number in skb_shinfo(skb)->tskey. Because an skbuff
351 ----------------------------
374 feature. At least one field is non-zero at any time. Most timestamps
381 as linuxptp. For the PTP clock API, see Documentation/driver-api/ptp.rst.
418 is the first if ts[2] is non-zero, the second otherwise, in which
446 Reading from the error queue is always a non-blocking operation. To
482 the requested fine-grained filtering for incoming packets is not
509 /* possible values for hwtstamp_config->tx_type */
527 /* possible values for hwtstamp_config->rx_filter */
547 --------------------------------------------------------
567 - In hard_start_xmit(), check if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
568 is set no-zero. If yes, then the driver is expected to do hardware time
570 - If this is possible for the skb and requested, then declare
572 SKBTX_IN_PROGRESS in skb_shinfo(skb)->tx_flags , e.g. with::
574 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
580 - Driver should call skb_tx_timestamp() as close to passing sk_buff to hardware
583 - As soon as the driver has sent the packet and/or obtained a
595 ----------------------------------------------------------
612 interface (redirecting to the host port on TX, and intercepting frames on RX).
615 suffer, since the switch's variable queuing delay introduces a path delay
636 - ``.port_txtstamp()``: a hook called prior to the transmission of
638 This is required for two-step timestamping, since the hardware
641 packet so that it can re-enqueue the packet back into the socket's
644 in skb->cb and enqueue a tx skb queue. Typically, a switch will have a
647 key-value pairs of PTP sequence ID/message type/domain number and the
655 One-step TX timestamping do not require packet cloning, since there is
656 no follow-up message required by the PTP protocol (because the
659 to be re-enqueued into its socket's error queue.
661 - ``.port_rxtstamp()``: On RX, the BPF classifier is run by DSA to
666 timestamps might either be available in-band (through metadata in the
667 DSA header, or attached in other ways to the packet), or out-of-band
668 (through another RX timestamping FIFO). Deferral on RX is typically
683 mii_timestamper`` and add a pointer to it in ``phydev->mii_ts``. The presence
691 - Checking, in ``.ndo_eth_ioctl``, whether ``phy_has_hwtstamp(netdev->phydev)``
695 - On RX, special intervention may or may not be needed, depending on the
698 ``skb_defer_rx_timestamp(skb)`` is necessary or not - and if it is, don't
700 enabled, and ``skb->dev->phydev->mii_ts`` exists, its ``.rxtstamp()`` hook
702 deferral for RX timestamping is necessary. Again like DSA, it becomes the
711 - On TX, again, special intervention might or might not be needed. The
712 function that calls the ``mii_ts->txtstamp()`` hook is named
733 Stacked PHCs, especially DSA (but not only) - since that doesn't require any
735 all possible code paths - is that they uncover bugs which were impossible to
739 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
750 the ``.ndo_eth_ioctl`` ("``priv->hwtstamp_tx_enabled == true``") and the
751 current skb requires a TX timestamp ("``skb_shinfo(skb)->tx_flags &
753 "``skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS``" flag. Note: as
761 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``" was set. With a stacked
768 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``", but also for
769 "``priv->hwtstamp_tx_enabled == true``". Because the rest of the system ensures