GNU bug report logs - #38492
27.0.50; Warn pdumper users when pure space has been overflowed

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Message #46 received at 38492 <at> debbugs.gnu.org (full text, mbox):

From: "Daniel Colascione" <dancol <at> dancol.org>
To: "Stefan Monnier" <monnier <at> iro.umontreal.ca>
Cc: 38492 <at> debbugs.gnu.org, eliz <at> gnu.org, dancol <at> dancol.org,
 Richard Stallman <rms <at> gnu.org>, kevin.legouguec <at> gmail.com
Subject: Re: bug#38492: 27.0.50; Warn pdumper users when pure space has been
 overflowed
Date: Sun, 15 Dec 2019 12:45:00 -0800

>> With portable dumping.  I think pure space provides no benefit.
>
> AFAICT, the purespace provides the same benefit with portable dumping as
> it does with unexec.  The benefit is to save time during the GC by not
> traversing the purespace.  It's basically an "old" generation in a kind
> of very restricted form of generational GC.
>
> Maybe purespace is too small compared to typical heap sizes to make
> a significant difference, nowadays.

I think the ratio of dumped-heap to runtime-heap is high enough these days
that the pure optimization you're describing doesn't really matter. I
think we need a better general-purpose GC that does generational tracking
even after the dump and without purespace's restriction against
intergenerational pointers. Whether that's something we reuse or write, I
don't know yet, but I have some ideas for how we can combine these
techniques with our conservative stack scanning.

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