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Date: Mon, 10 Jun 2024 11:38:50 -0500
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On 6/10/2024 2:04 AM, Anton Ertl wrote:
> Terje Mathisen <terje.mathisen@tmsw.no> writes:
>> Modern Unix typically provides 64-bit time_t seconds and a (effectively) =
>>
>> 30-bit ns field, so you can store them in a 96-bit container but I don't =
>>
>> think anyone does that?
> 
> man time_t tells me:
> 
> |time_t
> |              ...
> |              Used for time in seconds.  According to POSIX, it  shall  be  an
> |              integer type.
> 
> |timespec
> |              ...
> |              struct timespec {
> |                  time_t  tv_sec;  /* Seconds */
> |                  long    tv_nsec; /* Nanoseconds */
> |              };
> |
> |              Describes times in seconds and nanoseconds.
> |
> |              Conforming to: C11 and later; POSIX.1-2001 and later.
> 
> So if you have a 64-bit time_t, the C standard does that, and POSIX
> does it earlier.  Typical ABIs pad struct timespec to 128 bits,
> though.
> 

Can note, that I was mostly doing 64-bit time in microseconds for 
internal use.

This doesn't change the interface for gettimeofday or clock_gettime().


But, I guess, if nanoseconds is relevant, a nanosecond timer could be 
provided; but would not be terribly useful on a CPU with a 20ns clock 
cycle (will be stale well before one can do anything with it).


> - anton