Re: Larger GC thresholds for non-interactive Emacs

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@gmail.com>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,  Mattias Engdegård
>  <mattiase@acm.org>,  Eli Zaretskii <eliz@gnu.org>,  Tim Cross
>  <theophilusx@gmail.com>,  rms@gnu.org,  Alan Mackenzie <acm@muc.de>,
>   emacs-devel <emacs-devel@gnu.org>
> Date: Sun, 19 Jun 2022 15:25:15 +0800
> 
> I feel that I am confused about this data.
> 
> We have gc-cons-threshold and gc-cons-percentage
> 
> According to the gc-cons-percentage docstring:
> 
> >> If this portion is smaller than `gc-cons-threshold', this is ignored.
> 
> which implies that gc-cons-percentage only takes effect when
> heap_size * gc-cons-percentage >= gc-cons-threshold (= 0.8M)
> 
> So, heap_size should be >= 80M to take effect at p=1.0
> and heap_size should be >= 800M to take effect at p=0.1
> 
> yet, you do see an effect at total=18.5M.
> 
> What am I missing?

gc-cons-percentage is measured in units of 1, not in percents.  So the
value of 1.0 means that the condition

   heap_size * gc-cons-percentage >= gc-cons-threshold (= 0.8M)

will become true whenever heap_size is 0.8MB, not 80MB.