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Re: MPS codegen
From: |
Eli Zaretskii |
Subject: |
Re: MPS codegen |
Date: |
Sat, 15 Jun 2024 09:11:03 +0300 |
> From: Helmut Eller <eller.helmut@gmail.com>
> Cc: gerd.moellmann@gmail.com, acorallo@gnu.org, emacs-devel@gnu.org
> Date: Fri, 14 Jun 2024 21:26:37 +0200
>
> On Fri, Jun 14 2024, Eli Zaretskii wrote:
>
> > More generally, what exactly has been changed wrt loading from the
> > pdumper file since commit 219f7d5?
>
> The file is first loaded (mostly) as before; then all objects from the
> hot section are copied to a MPS managed region. Finally the hot section
> is discarded.
Can't we instead tell MPS not to move or manage any objects loaded
from the pdumper file? That's basically what we do now on master: any
object loaded from the pdumper file is considered immutable.
> My hypothesis is that discard_dump is the problem. The hot section
> probably contains something that isn't properly copied and
> dump_discard_mem seems to be a bit different on Windows. Why it even
> works on Linux is a mystery to me :-).
The Windows code decommits the memory region and makes it
inaccessible. By contrast, the posix_madvise method is AFAIU just an
advisory, and doesn't necessarily make the memory inaccessible.
Moreover, the Linux man page says:
In glibc, this function is implemented using madvise(2).
However, since glibc 2.6, POSIX_MADV_DONTNEED is treated as a no-
op, because the corresponding madvise(2) value, MADV_DONTNEED,
has destructive semantics.
So to do on Posix systems the same as we do on Windows, I think we
need to call madvise with MADV_DONTNEED, even if posix_madvise is
available, and also call mmap with PROT_NONE. Do you agree? If we do
that, does the GNU/Linux build still work, or does it also crash on
startup?
- Re: MPS codegen, (continued)
- Re: MPS codegen, Gerd Möllmann, 2024/06/14
- Re: MPS codegen, Helmut Eller, 2024/06/14
- Re: MPS codegen, Eli Zaretskii, 2024/06/14
- Re: MPS codegen, Eli Zaretskii, 2024/06/14
- Re: MPS codegen, Helmut Eller, 2024/06/14
- Re: MPS codegen, Gerd Möllmann, 2024/06/14
- Re: MPS codegen, Eli Zaretskii, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Eli Zaretskii, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen,
Eli Zaretskii <=
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Eli Zaretskii, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Helmut Eller, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Helmut Eller, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/15
- Re: MPS codegen, Gerd Möllmann, 2024/06/16