From: Noah Goldstein <goldstein.w.n@gmail.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: binutils@sourceware.org
Subject: Re: [PATCH 0/4] elf: Use mmap to map in section contents
Date: Tue, 5 Mar 2024 11:03:14 -0600 [thread overview]
Message-ID: <CAFUsyf+VBnvi2_jJ1i8H=F+JYB6oSTmx7nArXxWH8isjFGCAsw@mail.gmail.com> (raw)
In-Reply-To: <20240305170057.292800-1-hjl.tools@gmail.com>
On Tue, Mar 5, 2024 at 11:01 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> We can use mmap to map in ELF section contents, instead of copying them
> into memory by hand. We don't need to cache symbol nor relocation tables
> if they are mapped in. Data to link the 3.5GB clang executable in LLVM
> 17 debug build on Linux/x86-64 with 32GB RAM is:
>
> stdio mmap improvement
> user 86.73 87.02 -0.3%
> system 9.55 9.21 3.6%
> total 100.40 97.66 0.7%
> maximum set(GB) 17.34 13.14 24%
> page faults 4047667 3042877 25%
>
> and data to link the 275M cc1plus executable in GCC 14 stage 1 build is:
>
> user 5.41 5.44 -0.5%
> system 0.80 0.76 5%
> total 6.25 6.26 -0.2%
> maximum set(MB) 1323 968 27%
> page faults 323451 236371 27%
>
> Data shows that these won't improve the single copy linker performance.
> But they improve the overall system performance when linker is used by
> reducing linker memory usage and page faults. They allow more parallel
> linker jobs on LLVM debug build.
>
> Here is a quote from Noah Goldstein: "on a large project they are an
> extremely large speedup".
For reference, it is ~2x speedup of link step of LLVM head on debug build.
>
> H.J. Lu (4):
> elf: Use mmap to map in read-only sections
> elf: Add _bfd_elf_mmap_section and _bfd_elf_munmap_section_contents
> elf: Use mmap to map in symbol and relocation tables
> elf: Don't cache symbol nor relocation tables with mmap
>
> bfd/bfd-in2.h | 43 ++++++--
> bfd/bfd.c | 17 +++
> bfd/bfdio.c | 16 +--
> bfd/bfdwin.c | 8 +-
> bfd/cache.c | 11 +-
> bfd/compress.c | 2 +-
> bfd/elf-bfd.h | 11 ++
> bfd/elf-eh-frame.c | 4 +-
> bfd/elf-sframe.c | 4 +-
> bfd/elf.c | 256 +++++++++++++++++++++++++++++++++++++--------
> bfd/elf32-i386.c | 6 +-
> bfd/elf64-x86-64.c | 10 +-
> bfd/elfcode.h | 7 +-
> bfd/elflink.c | 72 ++++++++-----
> bfd/elfxx-target.h | 6 +-
> bfd/elfxx-x86.c | 7 +-
> bfd/elfxx-x86.h | 1 +
> bfd/libbfd-in.h | 32 ++++++
> bfd/libbfd.c | 247 ++++++++++++++++++++++++++++++++++++++++++-
> bfd/libbfd.h | 36 ++++++-
> bfd/linker.c | 7 +-
> bfd/lynx-core.c | 2 +-
> bfd/opncls.c | 25 ++++-
> bfd/section.c | 24 ++++-
> 24 files changed, 721 insertions(+), 133 deletions(-)
>
> --
> 2.44.0
>
next prev parent reply other threads:[~2024-03-05 17:03 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-05 17:00 H.J. Lu
2024-03-05 17:00 ` [PATCH 1/4] elf: Use mmap to map in read-only sections H.J. Lu
2024-03-05 17:00 ` [PATCH 2/4] elf: Add _bfd_elf_mmap_section and _bfd_elf_munmap_section_contents H.J. Lu
2024-03-05 17:00 ` [PATCH 3/4] elf: Use mmap to map in symbol and relocation tables H.J. Lu
2024-03-05 17:00 ` [PATCH 4/4] elf: Don't cache symbol nor relocation tables with mmap H.J. Lu
2024-03-05 17:03 ` Noah Goldstein [this message]
2024-03-06 0:50 ` [PATCH 0/4] elf: Use mmap to map in section contents Alan Modra
2024-03-06 16:16 ` H.J. Lu
2024-03-06 20:51 ` H.J. Lu
2024-03-06 4:45 ` Sam James
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