From: Mike Brady <4265913+mikebrady@users.noreply.github.com> Date: Tue, 6 Jul 2021 15:52:44 +0000 (+0100) Subject: Update README.md X-Git-Tag: 1.2~116 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=14b704685eb76b84bac52f05b576c6594bf37080;p=thirdparty%2Fnqptp.git Update README.md --- diff --git a/README.md b/README.md index 2c2e2bb..7f8f559 100644 --- a/README.md +++ b/README.md @@ -1,5 +1,7 @@ # NQPTP – Not Quite PTP -The `nqptp` daemon monitors PTP traffic. Briefly, `nqptp` monitors the times of any [PTP](https://en.wikipedia.org/wiki/Precision_Time_Protocol) clocks – up to 32 – it sees on ports 319 and 320. It maintains records for each clock, identified by its Clock ID and IP. Information about the *master clock* is provided in a [POSIX shared memory](https://pubs.opengroup.org/onlinepubs/007908799/xsh/shm_open.html) interface at `/nqptp`. +`nqptp` monitors PTP traffic. Briefly, `nqptp` monitors timing data from any [PTP](https://en.wikipedia.org/wiki/Precision_Time_Protocol) clocks – up to 32 – it sees on ports 319 and 320. It maintains records for each clock, identified by its Clock ID and IP. + +Information about the *master clock* is provided in a [POSIX shared memory](https://pubs.opengroup.org/onlinepubs/007908799/xsh/shm_open.html) interface at `/nqptp`. A timing peer list can be sent to `nqptp` over port 9000. The list consists of the letter 'T' followed by a space-separated list of the IP numbers of the timing peers. The list *completely replaces* any existing timing peer list. @@ -30,7 +32,7 @@ $ make The `make install` installs a `systemd` startup script. You should enable it and start it in the normal way. Note that `nqptp` must run in `root` mode to be able to access ports 319 and 320. # Notes -If you wish to use the shared mutex to ensure records are not altered while you are accessing them, you should open your side of the shared memory interface with read-write permission. Be aware that while your program has the mutex lock, it is in a "critical region" wherer it can halt `nqptp`, so keep any activity while you have the lock very short and very simple, e.g. copying it to local memory. +If you wish to use the shared mutex to ensure records are not altered while you are accessing them, you should open your side of the shared memory interface with read-write permission. Be aware that while your program has the mutex lock, it is in a "critical region" where it can halt `nqptp`, so keep any activity while you have the lock very short and very simple, e.g. copying it to local memory. Clock records not updated for a period are deleted.