Specify maxpoll for HW timestamping (default minpoll + 1) to track the
PHC well even when there is little NTP traffic on the interface. After
each PHC reading schedule a timeout according to the maxpoll. Polling
between minpoll and maxpoll is still triggered by HW timestamps.
Wait for the first HW timestamp before adding the timeout to avoid
polling PHCs on interfaces that are enabled in the configuration but
not used for NTP. Add a new scheduling class to separate polling of
different PHCs to avoid too long intervals between processing I/O
events.
In a non-tty session with chronyc it is not possible to detect the
end of the response without relying on timeouts, or separate responses
to a repeated command if using the -c option.
Add -e option to end each response with a line containing a single dot.
Add a new test for maximum delay using a long-term estimate of a
p-quantile of the peer delay. If enabled, it replaces the
maxdelaydevratio test. It's main advantage is that it is not sensitive
to outliers corrupting the minimum delay.
As it can take a large number of samples for the estimate to reach the
expected value and adapt to a new value after a network change, the
option is recommended only for local networks with very short polling
intervals.
With the first interleaved response coming after a basic response the
client is forced to select the four timestamps covering most of the last
polling interval, which makes measured delay very sensitive to the
frequency offset between server and client. To avoid corrupting the
minimum delay held in sourcestats (which can cause testC failures),
reject the first interleaved response in the client/server mode as
failing the test A.
This does not change anything for the symmetric mode, where both sets of
the four timestamps generally cover a significant part of the polling
interval.
Add "local" option to specify that the reference clock is an
unsynchronized clock which is more stable than the system clock (e.g.
TCXO, OCXO, or atomic clock) and it should be used as a local standard
to stabilize the system clock.
Handle the local refclock as a PPS refclock locked to itself which gives
the unsynchronized status to be ignored in the source selection. Wait
for the refclock to get at least minsamples samples and adjust the clock
directly to follow changes in the refclock's sourcestats frequency and
offset.
There should be at most one refclock specified with this option.
Report the number of received interleaved requests and current timestamp
count with their span.
Expand the serverstats description in chronyc man page.
Instead of keeping one pair of RX and TX timestamp for each address, add
a separate RX->TX map using an ordered circular buffer. Save the RX
timestamps as 64-bit integers and search them with a combined linear
interpolation and binary algorithm.
This enables the server to support multiple interleaved clients sharing
the same IP address (e.g. NAT) and it will allow other improvements to
be implemented later. A drawback is that a single broken client sending
interleaved requests at a high rate (without spoofing the source
address) can now prevent clients on other addresses from getting
interleaved responses.
The total number of saved timestamps does not change. It's still
determined by the clientloglimit directive. A new option may be added
later if needed. The whole buffer is allocated at once, but only on
first use to not waste memory on client-only configurations.
Use the new cmdparse function for parsing the (cmd)allow/deny commands
and refactor the code a bit to reduce the number of functions needed for
all the (cmd)allow/deny(all) combinations.
When separate client and server instances of chronyd are running on one
computer (e.g. for security or performance reasons) and are synchronized
to each other, the server instance provides a reference ID based on the
local address used for synchronization of its NTP clock, which breaks
detection of synchronization loops for its own clients.
Add a "copy" option to specify that the server and client are closely
related, no loop can form between them, and the client should assume the
reference ID and stratum of the server to fix detection of loops between
the server and clients of the client.
Remove packet interval checks with long delays as the tests are much
more likely to end when the client is waiting for a response. Increase
the base delay to make selection with two sources more reliable.
Reported-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
