| Re: [chrony-dev] disable RX timestamp adjustment patch |
[ Thread Index |
Date Index
| More chrony.tuxfamily.org/chrony-dev Archives
]
- To: chrony-dev@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-dev] disable RX timestamp adjustment patch
- From: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
- Date: Tue, 26 May 2020 09:55:28 +0200
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590479734; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1qoODTOjClGkVTXcZ/vEmu0cS5UJACWueWl/4GFchx4=; b=WIrb4ufEN4FiJQvjdtteURMQ+y0CLz82mcZltWB0sdQg2n1cv0K++iAk+0NxeSryZuKExW 1Pta1U8WmlEbEvNcnbKZ+k9hGtDrHzt5NHQI+hCDA8tqEAzIDPz7VX/rPiroleAKyjmQoA 8WimzmKua6Lc9GC8RmYwd8sBi+fejfM=
On Mon, May 25, 2020 at 11:46:19PM -0500, Dan Drown wrote:
> This adds the "disablerxadjust" config option to hwtimestamp. This uses RX
> timestamps at the 1588 point (after SFD/before ethernet header) instead of
> the NTP point (after ethernet CRC). At 1G, this changes the timestamp (and
> RTT) by 752ns. To be symmetrical, you'd want this enabled on both the NTP
> server and client.
What is the use case for this option? Is it meant for testing or
debugging?
As NTP doesn't rely on HW support in switches/routers, it needs to
shift the timestamping point to the end of the packet to minimize the
error when the server and client are connected to the network with
different link speeds. If you know the link speed, you could use the
rxcomp option to make the adjustment manually.
If there is a good use case, please try to find a shorter name, update
also the documentation, and submit it as a git patch.
--
Miroslav Lichvar
--
To unsubscribe email chrony-dev-request@xxxxxxxxxxxxxxxxxxxx with "unsubscribe" in the subject.
For help email chrony-dev-request@xxxxxxxxxxxxxxxxxxxx with "help" in the subject.
Trouble? Email listmaster@xxxxxxxxxxxxxxxxxxxx.