Re: Tooltips GC overhead

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Cc: address@hidden,  address@hidden,  address@hidden
> Date: Tue, 04 Aug 2015 03:31:52 -0400
> 
> > And we could do that only when the memory profiler is invoked.
> 
> AFAICT it would require an extra test somewhere in Fcons, and that
> test will always have to be performed.

Just looking at the implementation of Fcons, I find it hard to believe
a single comparison can have any significant effect on its efficiency.
So I'm unsure how this could be of any practical concern.

> > In any case, it's much better than the current useless profile.
> 
> I'm not convinced it'd make it sufficiently better

Well, it allowed me in this case to identify the source of the problem
quickly, efficiently, and accurately.

> to justify the cost.

Please show the costs, then, and please do that with some kind of
quantitative analysis, so that we could have some numbers to discuss,
instead of just arguing about personal preferences and opinions.

> I'd be OK with adding this "more precise allocation profiler" as
> a compile-time option, so we could at least see if the improved
> precision does make it more useful.

IME, compile-time options of this kind are rarely useful, because they
are never there when you need them.  Especially if the person who
needs to perform measurements doesn't build their Emacs.