Re: Predictable Internet Time

Joe Touch <touch@xxxxxxx> · Fri, 21 Apr 2017 11:41:43 -0700



    On 4/21/2017 11:35 AM, Phillip
      Hallam-Baker wrote:

    
          On Fri, Apr 21, 2017 at 1:57 PM, Joe
            Touch <touch@xxxxxxx>
            wrote:

            
                On 4/21/2017 10:26 AM, Nico Williams wrote:

                > "Internet time" (that which we use in [new]
                Internet protocols) should

                > just be TAI.  And every existing Internet protocol
                should be updated to

                > indicate which time is used in practice, UTC or
                TAI, regardless of what

                > was originally specified.

              I would be very glad of we defined Internet Time as
              TAI, but also expect

              all protocols to understand both TAI and UTC if possible.

              
                  Joe

                
              To answer the issues raised:
              

              1) POSIX already has this
                pretty much covered
              

              http://pubs.opengroup.org/onlinepubs/009695399/functions/clock_getres.html
            
            
              int
                  clock_gettime(clockid_t clock_id, struct
                  timespec *tp);
            
             
          So all that is required is to
            define clock identifiers for:
          

          TAI (The total number of seconds
            elapsed since the start of the epoch)
          UTC (The TAI value adjusted for UTC
            leap seconds, i.e. number of non leap second seconds since
            the start of the epoch)
        
      
    If these aren't already included, I'm surprised (at least UTC).

    
          PIT (The TAI value adjusted for PIT
            leap seconds)
        
      
    We don't need PIT.

    
          POSIX already defines constants
            for CLOCK_PROCESS_CPUTIME_ID, CLOCK_REALTIME 
          

          All that is needed is to define the
            additional ones. 
          

          2) No I
            did not move the goalposts. My original proposal was to
            solve the needless chaos caused be the idiotic notion of
            changing the definition of time at six months notice. The
            stupidity of that notion should be apparent to all.
        
      
    There is no getting around the fact that the rest of the planet
    accepts leap seconds. If that's not something you want to track,
    then use TAI and be off-sync with the rest of the world when they
    use UTC.

    
    PIT does nothing helpful except add yet another level of indirection
    and confusion here.

    
          3) Screw
            the astronomers. Pluto is to a planet.
        
      
    IMO, this issue is sufficently driven by "rough consensus and
    running code" of the entire planet right now - where all governments
    already use UTC.

    
    Joe