Re: What is a typical precision of gettimeofday()?

Hannu Krosing <hannuk(at)google(dot)com> writes:
> At least "does it run" tests should be there -

> For example with the current toolchain on MacOS I was able to compile
> __builtin_readcyclecounter(); but it crashed when the result was
> executed.

> The same code compiled *and run* fine on same laptop with Ubuntu 24.04

> We might also want to have some testing about available speedups from
> pg_bitmanip.h being used, but that could be tricky to test in an
> universal way.

Keep in mind that pg_test_timing is not just some random exercise in a
vacuum. The point of it IMV is to provide data about the performance
one can expect from the instr_time.h infrastructure, which bears on
what kind of resolution EXPLAIN ANALYZE and other features have. So
if we did want to depend on read_tsc() or __builtin_readcyclecounter()
or what-have-you, the way to go about it would be to change
instr_time.h to compile code that uses that. I would consider that
to be a separate patch from what we're doing to pg_test_timing here.

regards, tom lane