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Re: When should ralloc.c be used?

From: Stefan Monnier
Subject: Re: When should ralloc.c be used?
Date: Sat, 29 Oct 2016 10:55:20 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux)

> E.g., it turned out that most of the time it takes 'loadup' to do its
> job is due to the linear search of pure strings in
> find_string_data_in_pure, called by make_pure_string.

Indeed.  hash-consing pure objects takes another very significant
percentage of the time.

> If we call 'loadup' upon every startup, the need for pure storage goes
> away, and the 'loadup' time can be sped up tenfold.

Actually, there's no *need* for pure storage in either case.

There are benefits to the use of pure storage, and some of them remain
even if we don't dump: one of the benefits that remains is to reduce the
size of the GC'd heap and hence speed up the GC.  Whether that's
significant enough to bother with it is of course debatable.  But note
also that we could keep the use of pure-space without paying the hefty
price of find_string_data_in_pure (or hash-consing), since these merely
try to make the purespace more compact.  The extra cost is OK when we
dump the result, but it's not worth the trouble if we don't dump.

> And that is even before making all of the preloaded files a single
> file, which speeds up things at least twofold more, according to
> my measurements.

BTW, how large is that single file (I'm curious if its size is
significantly different from the 3.2MB I got for my dumped.elc)?


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