Very slow check/nativecomp build

Very slow check/nativecomp build

[Lars Ingebrigtsen]

I first noticed this yesterday, and I don't know when it started, but
I'm pretty sure the compilation speed was normal some days ago, so I've
added Alan to the CCs because of the recent sym-with-pos change that was
applied a few days ago (but it may have nothing to do with anything).

With:

./configure --with-native-compilation --enable-checking=all

a make bootstrap -j16 takes:

real	15m46.201s
user	113m21.805s
sys	7m29.174s

It used to take 5 minutes on this machine.  I'm pretty sure?  Is anybody
else also seeing this, or am I totally misremembering how long it takes?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: Very slow check/nativecomp build

[Alan Mackenzie]

Hello, Lars.

On Sun, Feb 20, 2022 at 17:46:38 +0100, Lars Ingebrigtsen wrote:
> I first noticed this yesterday, and I don't know when it started, but
> I'm pretty sure the compilation speed was normal some days ago, so I've
> added Alan to the CCs because of the recent sym-with-pos change that was
> applied a few days ago (but it may have nothing to do with anything).

> With:

> ./configure --with-native-compilation --enable-checking=all

> a make bootstrap -j16 takes:

> real	15m46.201s
> user	113m21.805s
> sys	7m29.174s

> It used to take 5 minutes on this machine.  I'm pretty sure?  Is anybody
> else also seeing this, or am I totally misremembering how long it takes?

With the --enable-checking option?  Are you sure you're not remembering
it with just --with-native-compilation?  --enable-checking makes things
_much_ slower.

> -- 
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Very slow check/nativecomp build

[Stefan Monnier]

> --enable-checking makes things _much_ slower.

FWIW this has not always been the case, and it should be considered as
a bug (we' (well, Paul, mostly) have/has fixed such problems in the
past).

It's inevitable that it makes things slower, of course, but not by a factor 3.


        Stefan

Re: Very slow check/nativecomp build

[Lars Ingebrigtsen]

Alan Mackenzie <acm@muc.de> writes:

> With the --enable-checking option?  Are you sure you're not remembering
> it with just --with-native-compilation?  --enable-checking makes things
> _much_ slower.

Yes, I must be misremembering.  nativecomp without checking still takes
about five minutes, and I checked with a nativecomp build from a couple
months back -- it also takes about 14 minutes with nativecomp +
checking.

So I guess it's been a long while since I tried a build that had both
nativecomp and checking.

Sorry for the noise.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: Very slow check/nativecomp build

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Sun, 20 Feb 2022 19:02:58 +0100
> Cc: emacs-devel@gnu.org
> 
> Alan Mackenzie <acm@muc.de> writes:
> 
> > With the --enable-checking option?  Are you sure you're not remembering
> > it with just --with-native-compilation?  --enable-checking makes things
> > _much_ slower.
> 
> Yes, I must be misremembering.  nativecomp without checking still takes
> about five minutes, and I checked with a nativecomp build from a couple
> months back -- it also takes about 14 minutes with nativecomp +
> checking.

As Stefan points out, this shouldn't happen.  So we should try and
find the reason for such slowdown from using --enable-checking.

Re: Very slow check/nativecomp build

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> As Stefan points out, this shouldn't happen.  So we should try and
> find the reason for such slowdown from using --enable-checking.

I wondered whether the 3x increase with --enable-checking=all was a
nativecomp phenomenon, but it seems to be the same without nativecomp.
It takes 2:30 to built the trunk with just ./configure, and about 8
minutes with checking.

I tried the same in emacs-28, and it's much the same story there:
Without checking, it's 2:20, and with checking it's 6:50.  So it's not a
new phenomenon that checking adds a multiplier to the build time, but it
seems to be worsening somewhat.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no