bug#46881: 28.0.50; pdumper dumping causes way too many syscalls

[Pip Cet]

On Thu, Mar 4, 2021 at 10:26 PM Daniel Colascione <dancol@dancol.org> wrote:
> On 3/3/21 12:51 AM, Eli Zaretskii wrote:
> > Daniel, Paul: any comments?  In particular, is it safe to allocate
> > large amounts of memory off the heap while dumping?  A couple of
> > places in pdumper.c says some parts of code should call malloc.
>
> It looks fine, but wouldn't dumping to a FILE* (with internal buffering)
> do the same basic thing in a simpler way?

I initially set out to do that, but decided against it. We don't just
write sequentially (when FILE I/O helps, a little), we also have the
seek-and-fixup phase, and it didn't seem any simpler at that point..

> There aren't any particular
> constraints on the environment _during_ the dump: we even make new lisp
> objects. It's when loading the dump, early in initialization, that you
> have to be careful.

Thanks!

Pip