On Mon, Mar 20, 2023, 2:31 AM Yuan Fu <casouri@gmail.com> wrote:

>
>
> > On Mar 19, 2023, at 6:18 PM, Lynn Winebarger <owinebar@gmail.com> wrote:
> >
> > I've
> > done this manually on various systems I use with a significant
> > improvement in startup performance.
>
> It'll be interesting to see the numbers on the improvement. How much does
> it improve startup time if there is x packages and y are loaded at startup
> time?
>


Good question. The systems I've done this manually on are one-off builds of
28.x on sandboxed systems where the system emacs is 24.3.  So, I didn't
have to worry about managing package updates with any frequency.

I'm now working on unsandboxed systems where the system version is 27.2 and
I've installed 28.x, 29.x and 30.x builds into /use/local.  I don't want to
do a manual installation here because I (would like to) regularly update
packages with the package menu.   Additionally I discovered that 30.x (and
probably 29.x) has introduced a new bytecode instruction, after installing
packages under 30.x then trying to run 28.x.  So I've set up my
initialization files to use different custom-files, package archive
directories, and package-quickstart.el files tied to the major version of
emacs that's running.  Running the install through
package-install-selected-packages for each version is incredibly slow, but
seems the safest way for now.  Hence my interest in implementing a more
systematic approach now that doesn't rebuild a massive package-quickstart
file for every package installed.

I did file a bug report as a place to hang cpu and memory profiles of the
initialization when I loaded everything at startup under 27.2 - see
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=61004 .  If memory serves,
locate-file took something like 75% of the cpu time, and also did an
incredible (and dominant) amount of consing. Even if the autoloads in
package-quickstart specified a full path for the library (they don't),
every "require" of an unloaded system library still has to search the
entire 2403 (or however many were in that bug report) package directories
first, for every system library required, even if no packages are actually
loaded.

I'm using 28.x as my reference build because re-dumping has been broken
under 29.x.

Lynn