Re: Time to merge scratch/correct-warning-pos into master, perhaps?

[Alan Mackenzie]

Hello, Stefan.

On Sun, Feb 20, 2022 at 15:37:55 -0500, Stefan Monnier wrote:
> > I seem to have a default setting of 4kHz.  This was enough to get several
> > thousand hits in each build ("old" and "new") running the test suite.  As
> > I wrote in my post just now to Eli, the results came up contrary to what
> > was expected - the "old" build, running the simple EQ spent more time in
> > it than the "new" build running the complicated EQ.  Possibly I've made
> > some silly mistake in the measurements.

> Maybe it's because EQ was used for NILP before but isn't used for it
> any more?

Bingo!  That's surely the reason.  In the new build, NILP wasn't using
EQ.  I'll sort that out and compare again.  Just not tonight.

Thank you very much!

> In any case, in my experience measuring such things is wickedly
> difficult.  It's even hard to define what it is we really want to
> measure because the impact will depend so heavily of how the code gets
> inlined&scheduled by the compiler and then how it gets scheduled in the
> CPU, and how branch prediction interacts with it, etc...

I think I'm just trying to get some sort of handle on how much the code
has slowed down because of EQ.  Obviously, making EQ into a function
(rather than an inline function) will have distorted things, but it
seems the easiest way of measuring something at the moment.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).