[LEAPSECS] My FOSDEM slides

[Joseph Gwinn]

On Sun, 01 Mar 2015 22:25:36 +0000, Harlan Stenn wrote:
> Joseph Gwinn writes:
>> On Sun, 01 Mar 2015 20:35:20 +0000, Harlan Stenn wrote:
>> Once people get a system to work, they don't tend to go fixing things 
>> that ain't broke.
> 
> There's breakage they know about and breakage they don't know about...
> 
>>>> 2.  Slide titled ""Possibilities for Future Improvements (2)":  In the 
>>>> wish list for a kernel call to ask if the kernel runs UTC or TAI, a 
>>>> couple of issues come to mind.  First, many systems set the GPS 
>>>> receiver to emit GPS System Time via NTP (and IRIG), so a GPS System 
>>>> Time option may be needed.  Second, we often have the GPS (or PTP 1588) 
>>>> receiver to emit GPS System Time, but never share this with downstream 
>>>> servers, who are configured for UTC (but strangely the leap seconds 
>>>> never come).  The difference between UTC and GPS System Time is handled 
>>>> in applications code.  The reason for this approach is so that the bulk 
>>>> of the system is free from step discontinuities, and only the 
>>>> interfaces need deal with UTC.
>>> 
>>> This issue is also address by NTF's General Timestamp API, as
>>> "timescale" is one of the data elements of this timestamp.  We have
>>> already done a proof-of-concept to get these timestamps used as the core
>>> part of the kernel timekeeping API.  There is clearly more work to be
>>> done here.  We know how to do this work, we just need technical and
>>> financial support to make it happen.
>> 
>> Great.  Is this API a parallel to the named clock interface of POSIX, 
>> where the OS kernel vendor can add named clocks that are not in the 
>> POSIX standard - what is standardized is the mechanism for defining and 
>> using special purpose clocks unknown to POSIX.
> 
> I haven't looked, and my instant thought is that the POSIX named
> clock interface could trivially use the GTSAPI.  The timestamps provided
> would include both a timescale and a "clock ID".

Can you provide a link to where this General Timestamp API is defined?  
I'll look it over.

Thanks,

Joe Gwinn