From: "H.J. Lu" <hjl.tools@gmail.com>
To: binutils@sourceware.org
Cc: goldstein.w.n@gmail.com
Subject: [PATCH 0/4] elf: Use mmap to map in section contents
Date: Tue, 5 Mar 2024 09:00:53 -0800 [thread overview]
Message-ID: <20240305170057.292800-1-hjl.tools@gmail.com> (raw)
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".
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 reply other threads:[~2024-03-05 17:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-05 17:00 H.J. Lu [this message]
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 ` [PATCH 0/4] elf: Use mmap to map in section contents Noah Goldstein
2024-03-06 0:50 ` 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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