Re: Use CLOCK_MONOTONIC_COARSE for instr_time when available

[wenhui qiu]

>
> HI
>
> > As far as I know, our usage of instr_time really needs the highest
> resolution available, because we are usually trying to measure pretty
> short intervals.  You say that this patch reduces execution time,
> and I imagine that's true ... but I wonder if it doesn't do so at
> the cost of totally destroying the reliability of the output numbers.
i strongly agree ，It seems like focusing on the small stuff while missing
the big pictur