Re: Enabling native compilation by default when libgccjit is present

[Arthur Miller]

"Jose A. Ortega Ruiz" <jao@gnu.org> writes:

> On Sun, Dec 05 2021, Tim Cross wrote:
>
>> Lars Ingebrigtsen <larsi@gnus.org> writes:
>>
>>> Po Lu <luangruo@yahoo.com> writes:
>>>
>>>>> Most distributions will probably release Emacs 28.1 with native
>>>>> compilation switched on.
>>>>
>>>> Why is that so?  Most distributions only build their Emacs packages with
>>>> the default options.
>>>
>>> Several distributions have signalled that they want to ship Emacs with
>>> native compilation switched on (and at least one said they're going to
>>> be doing a full ahead-of-time build, if I remember correctly) --
>>> presumably because that'll give their users a faster Emacs.
>>
>> Does it actually give that much of a performance boost? It has been a
>> couple of months since I tried native compilation in Emacs 28, but when
>> I did, I noticed next to no performance improvement at all. In fact, all
>> I did notice was lots of warnings and significant delays whenever I
>> updated packages.
>
> FWIW, i've used native compilation in master builds on and off for a
> couple of months, on GNU/Linux (debian sid), and haven't noticed any
> speed difference either. Last time was this week.  The warnings are
> gone, not sure if it's because i configured some flag back in the day or
> because it's now the default, and the compilation delays are not too
> bad; but, as i said, i don't notice any difference other than the fact
> that the RAM comsumption of emacs is about 80% higher for long sessions
> when i use native compilation (i use emacs for virtually everything,
> it's my X11 desktop environment, and have a moderate amount of packages
> installed (around 50, i think)).
>
>> I've actually never noticed any speed problems with Emacs. Where there
>> are delays, it is due to the synchronous nature of what I'm doing rather
>> than basic performance.
>
> That's also mostly my experience.  The only times i have to wait a bit
> (some seconds) are for eww to render some pages (and that doesn't happen
> often), and those waiting times don't seem to change at all when i
> enable native compilation.
>
> I'd be curious to know where people are seeing speedups.

I see speedups in like entire Emacs experience, since the very first
incarnation of 'gccemacs' when Andrea announced it.

When I sometimes compile Emacs without native compiler just to test or compare
something it feels like I will never go back to Emacs without native compiler if
I don't have to. It is not like the native compiler enabled something I couldn't
do before, if it is than it is not my use-case, so I am not aware of it. But it
is overal resposivness of Emacs, in Helm completions, searches, etc. I haven't
done som formal benchmarks, but for me it feels more responsive and speedier
especially when there are lots of files and buffers.

It depends on how one use Emacs of course. Personally I use Emacs for almost
everything I do on the computer, and I like Helm, so there is a lot of
completions and searches I do.