Re: Preview: portable dumper

[Daniel Colascione]

On 10/19/2017 03:12 AM, Jeremie Courreges-Anglas wrote:
> On Wed, Oct 18 2017, Kaushal Modi <address@hidden> wrote:
> > @Daniel
> >
> > Just bumping the thread. Would like to know what came out of this.
>
> Same here.  I don't really care whether the portable dumper or the "big
> .elc file" approach is taken, but it would be cool to see emacs out of
> the malloc and unexec business.  This code is fragile and tends to break
> on less popular platforms (OpenBSD in my case).

I've pushed the portable dumper to the pdumper Savannah branch. It 
should support a fully PIC Emacs.

I implemented demand-paging logic and backed all of it out: the demand 
paging worked fine, but I wasn't able to figure out a good way to get GC 
not to page in the whole region almost immediately anyway. I was 
surprised to find that my Emacs GCs almost immediately after start.

Timing on the current code is nevertheless pretty good. Running emacs -Q 
-nw -batch --eval '(progn (garbage-collect) (kill-emacs))' 100 times,

  unexec: 22.47ms per invocation
  pdumper: 28.19ms per invocation

I think this degree of startup overhead is acceptable.

I could implement the non-PIC mode I'd previously mentioned; I'm 
confident it would be faster than unexec. But with PIC doing this well, 
why bother? We want a PIC Emacs for security reasons anyway.