GNU bug report logs - #54698
non-recursive GC marking [PATCH]

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Message #23 received at 54698 <at> debbugs.gnu.org (full text, mbox):

From: Mattias Engdegård <mattiase <at> acm.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: larsi <at> gnus.org, 54698 <at> debbugs.gnu.org
Subject: Re: bug#54698: non-recursive GC marking [PATCH]
Date: Mon, 4 Apr 2022 13:57:54 +0200

4 apr. 2022 kl. 13.38 skrev Eli Zaretskii <eliz <at> gnu.org>:

> What happens with data that GC relocates, like when it relocates and
> compacts string data?  If the relocated data is allocated on the heap
> after the simulated stack, the original string data, which is now free
> memory, will be "trapped" behind the simulated stack, and 'free' will
> be unable to return it to the OS.  This could make the memory
> footprint of Emacs larger than it could be.

That effect is unlikely to be visible. I don't think a single (and not very big) allocation would contribute materially to heap fragmentation, given the amount of allocation being made all the time. (But prove me wrong!)

> Was this aspect considered and audited/tested?

Do you have a test case?

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