From: Hal Murray
david-tay...@blueyonder.co.uk said:
Perhaps because NTP sees the offset in both send and receive packets and
therefore, like any other network delay, it is subtracted out.
The description of the change was to remove a delay on the receive side.
There was no mention of a
On Thu, Mar 26, 2015 at 4:10 AM, David J Taylor
david-tay...@blueyonder.co.uk wrote:
Yes, I see what you mean.
I haven't parsed the driver but asymmetry inverts the sign of the offset as
viewed from each end (when each end is S1) so it's usually obvious. I'm
not seeing it. I've always used
david-tay...@blueyonder.co.uk said:
I was really interested to see how much effect the extra Ethernet latency of
the Raspberry Pi added in a real-world scenario. Thanks to Philip
Gladstone, I have now discovered a way of significantly reducing that
latency, so that the delay reported by NTP
From: Hal Murray
http://www.satsignal.eu/ntp/RaspberryPi-notes.html#EthernetLatency
Thanks for the tip. I did that to my R Pi and I see the same improvement in
round trip time.
What I don't understand is why the time offset as measured by an outside
system didn't change. ??
On Wed, Mar 25, 2015 at 3:22 AM, Hal Murray hmur...@megapathdsl.net wrote:
What I don't understand is why the time offset as measured by an outside
system didn't change. ??
NTP always and continuously measures the round trip time over the network
and assumes the one-way time is 1/2 the
On Wed, 25 Mar 2015 09:46:05 -0700
Chris Albertson albertson.ch...@gmail.com wrote:
So if NTP always compensates for network delay why do you get improved
performance with less delay? That is because what messes up NTP is
uncertainly in the delay and likely it's the case that reducing the
What I don't understand is why the time offset as measured by an
outside system didn't change. ??
david-tay...@blueyonder.co.uk said:
Perhaps because NTP sees the offset in both send and receive packets and
therefore, like any other network delay, it is subtracted out.
The description of
From: Neil Schroeder
The other key key key item is make sure you hand build yourself a 3.14 or
.16 kernel.
NS
=
Thanks, Neil. I'm afraid I have neither the expertise nor the patience to
do that, and to an extent this was intended to be an out-of-the-box
Folks,
Many thanks for all your comments. I am now undertaking tests with the
stripped-down Console build of the OS. With both the RPi and the BBB I
started with what the typical user might install rather than any special
version (indeed, it's built into the BBB). It seems that while many
David:
On this page:
http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#BBW.2FBBB_.28All_Revs.29
they list an alternative console only image:
https://rcn-ee.com/rootfs/bb.org/release/2015-03-01/console/bone-debian-7.8-console-armhf-2015-03-01-2gb.img.xz
It might be easier starting with
David:
On the BBB, were you running the fully loaded release, or the minimum
console version of the OS?
Which specific version of the OS?
Thanks,
--- Graham
=
Graham,
The download was:
bone-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img.xz (547,024,548 bytes)
David:
On this page:
http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#BBW.2FBBB_.28All_Revs.29
they list an alternative console only image:
https://rcn-ee.com/rootfs/bb.org/release/2015-03-01/console/bone-debian-7.8-console-armhf-2015-03-01-2gb.img.xz
It might be easier starting with
On Sun, 22 Mar 2015 09:29:56 -0400
Mike George mgeo...@tuffmail.us wrote:
On this page:
http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#BBW.2FBBB_.28All_Revs.29
they list an alternative console only image:
I can confirm similar issues with each of my BBBs. They just can't seem to
get the jitter down.
I've tried a variety of combinations of Debian and Ubuntu, and even
replaced the clock on one with an Si5338.
On Sun, Mar 22, 2015 at 6:29 AM, Mike George mgeo...@tuffmail.us wrote:
David:
On
David:
If you are running headless, that is, not using the on board
video-graphics system,
all interaction with the unit is via the console, local or SSH.
In this case, I would use the console version as described above. It is
about
one tenth the size of the version you are using.
You will
David:
On this page:
http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#BBW.2FBBB_.28All_Revs.29
they list an alternative console only image:
https://rcn-ee.com/rootfs/bb.org/release/2015-03-01/console/bone-debian-7.8-console-armhf-2015-03-01-2gb.img.xz
It might be easier starting with
What kernel do you use? And what scheduling configuration?
As it is a timing application, and sensible to jitter, I would suggest
to use a real-time kernel (e.g. Preempt RT) [1].
Usually one can find pre-built kernels with PreempRT-support for boards
like the RPi etc. on the internet.
If you
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