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Diffstat (limited to 'HOWTO/INSTALL.md')
| -rw-r--r-- | HOWTO/INSTALL.md | 45 |
1 files changed, 28 insertions, 17 deletions
diff --git a/HOWTO/INSTALL.md b/HOWTO/INSTALL.md index 53b1b8cd8a..7efea77d4c 100644 --- a/HOWTO/INSTALL.md +++ b/HOWTO/INSTALL.md @@ -417,22 +417,33 @@ important when building Erlang/OTP. By default the VM will refuse to build if native atomic memory operations are not available. Erlang/OTP itself provides implementations of native atomic memory operations -that can be used when compiling with a `gcc` compatible compiler on 32-bit -and 64-bit x86, 32-bit and 64-bit SPARC V9, and 32-bit PowerPC. When compiling -with a `gcc` compatible compiler on other architectures, the VM may be able to -make use of native atomic operations using the `__sync_*` primitives, but this -should only be used as a last resort since this wont give you optimal -performance. When compiling on Windows using a MicroSoft Visual C++ compiler -native atomic memory operations are provided by Windows APIs. - -You are recommended to use the native atomic implementation provided by -Erlang/OTP, or the API provided by Windows. If these do not provide native -atomics on your platform, you are recommended to build and install -[libatomic_ops][] before building Erlang/OTP. The `libatomic_ops` library -provides native atomic memory operations for a variety of platforms and -compilers. When building Erlang/OTP you need to inform the build system of -where the `libatomic_ops` library is installed using the -`--with-libatomic_ops=PATH` configure switch. +that can be used when compiling with a `gcc` compatible compiler for 32/64-bit +x86, 32/64-bit SPARC V9, 32-bit PowerPC, or 32-bit Tile. When compiling with +a `gcc` compatible compiler for other architectures, the VM may be able to make +use of native atomic operations using the `__atomic_*` builtins (may be +available when using a `gcc` of at least version 4.7) and/or using the +`__sync_*` builtins (may be available when using a `gcc` of at least version +4.1). If only the `gcc`'s `__sync_*` builtins are available, the performance +will suffer. Such a configuration should only be used as a last resort. When +compiling on Windows using a MicroSoft Visual C++ compiler native atomic +memory operations are provided by Windows APIs. + +Native atomic implementation in the order preferred: +1. The implementation provided by Erlang/OTP. +2. The API provided by Windows. +3. The implementation based on the `gcc` `__atomic_*` builtins. +4. If none of the above are available for your architecture/compiler, you + are recommended to build and install [libatomic_ops][] before building + Erlang/OTP. The `libatomic_ops` library provides native atomic memory + operations for a variety of architectures and compilers. When building + Erlang/OTP you need to inform the build system of where the + `libatomic_ops` library is installed using the + `--with-libatomic_ops=PATH` `configure` switch. +5. As a last resort, the implementation solely based on the `gcc` + `__sync_*` builtins. This will however cause lots of expensive and + unnecessary memory barrier instructions to be issued. That is, + performance will suffer. The `configure` script will warn at the end + of its execution if it cannot find any other alternative than this. ### Building ### @@ -849,7 +860,7 @@ Copyright and License %CopyrightBegin% -Copyright Ericsson AB 1998-2014. All Rights Reserved. +Copyright Ericsson AB 1998-2015. All Rights Reserved. The contents of this file are subject to the Erlang Public License, Version 1.1, (the "License"); you may not use this file except in |