jemalloc/INSTALL

Building and installing jemalloc can be as simple as typing the following while
in the root directory of the source tree:

    ./configure
    make
    make install

=== Advanced configuration =====================================================

The 'configure' script supports numerous options that allow control of which
functionality is enabled, where jemalloc is installed, etc.  Optionally, pass
any of the following arguments (not a definitive list) to 'configure':

--help
    Print a definitive list of options.

--prefix=<install-root-dir>
    Set the base directory in which to install.  For example:

        ./configure --prefix=/usr/local

    will cause files to be installed into /usr/local/include, /usr/local/lib,
    and /usr/local/man.

--with-rpath=<colon-separated-rpath>
    Embed one or more library paths, so that libjemalloc can find the libraries
    it is linked to.  This works only on ELF-based systems.

--with-jemalloc-prefix=<prefix>
    Prefix all public APIs with <prefix>, so that, for example, malloc()
    becomes <prefix>malloc().  This makes it possible to use jemalloc at the
    same time as the system allocator.

--with-install-suffix=<suffix>
    Append <suffix> to the base name of all installed files, such that multiple
    versions of jemalloc can coexist in the same installation directory.  For
    example, libjemalloc.so.0 becomes libjemalloc<suffix>.so.0.

--enable-debug
    Enable assertions and validation code.  This incurs a substantial
    performance hit, but is very useful during application development.

--enable-stats
    Enable statistics gathering functionality.  Use the 'P' option to print
    detailed allocation statistics at exit.

--enable-prof
    Enable heap profiling and leak detection functionality.  Use the 'B', 'F',
    'I', 'L', and 'U' options to control these features.

--disable-prof-libgcc
    Disable the use of libgcc's backtracing functionality.  Ordinarily, libgcc's
    backtracing functionality is superior to the alternatives, but it may fail
    to capture backtraces on some systems.

--enable-prof-libunwind
    Use the libunwind library (http://www.nongnu.org/libunwind/) for stack
    backtracing.  libunwind is quite slow, but it tends to work across a wider
    variety of system configurations than the default backtracing code, which is
    based on libgcc functionality or gcc intrinsics.

--disable-tiny
    Disable tiny (sub-quantum-sized) object support.  Technically it is not
    legal for a malloc implementation to allocate objects with less than
    quantum alignment (8 or 16 bytes, depending on architecture), but in
    practice it never causes any problems if, for example, 4-byte allocations
    are 4-byte-aligned.

--disable-tcache
    Disable thread-specific caches for small and medium objects.  Objects are
    cached and released in bulk, thus reducing the total number of mutex
    operations.  Use the 'H' and 'G' options to control thread-specific caching.

--enable-swap
    Enable mmap()ed swap file support.  When this feature is built in, it is
    possible to specify one or more files that act as backing store.  This
    effectively allows for per application swap files.

--enable-dss
    Enable support for page allocation/deallocation via sbrk(2), in addition to
    mmap(2).

--enable-fill
    Enable support for junk/zero filling of memory.  Use the 'J' option to
    control junk filling, or the 'Z' option to control zero filling.

--enable-xmalloc
    Enable support for optional immediate termination due to out-of-memory
    errors, as is commonly implemented by "xmalloc" wrapper function for malloc.
    Use the 'X' option to control termination behavior.

--enable-sysv
    Enable support for System V semantics, wherein malloc(0) returns NULL
    rather than a minimal allocation.  Use the 'V' option to control System V
    compatibility.

--enable-dynamic-page-shift
    Under most conditions, the system page size never changes (usually 4KiB or
    8KiB, depending on architecture and configuration), and unless this option
    is enabled, jemalloc assumes that page size can safely be determined during
    configuration and hard-coded.  Enabling dynamic page size determination has
    a measurable impact on performance, since the compiler is forced to load
    the page size from memory rather than embedding immediate values.

--disable-lazy-lock
    Disable code that wraps pthread_create() to detect when an application
    switches from single-threaded to multi-threaded mode, so that it can avoid
    mutex locking/unlocking operations while in single-threaded mode.  In
    practice, this feature usually has little impact on performance unless
    thread-specific caching is disabled.

--disable-tls
    Disable thread-local storage (TLS), which allows for fast access to
    thread-local variables via the __thread keyword.  If TLS is available,
    jemalloc uses it for several purposes.  Not that disabling TLS implies
    --disable-tcache.

The following environment variables (not a definitive list) impact configure's
behavior:

CFLAGS="?"
    Pass these flags to the compiler.  You probably shouldn't define this unless
    you know what you are doing.  (Use EXTRA_CFLAGS instead.)

EXTRA_CFLAGS="?"
    Append these flags to CFLAGS.  This makes it possible to add flags such as
    -Werror, while allowing the configure script to determine what other flags
    are appropriate for the specified configuration.

    The configure script specifically checks whether an optimization flag (-O*)
    is specified in EXTRA_CFLAGS, and refrains from specifying an optimization
    level if it finds that one has already been specified.

CPPFLAGS="?"
    Pass these flags to the C preprocessor.  Note that CFLAGS is not passed to
    'cpp' when 'configure' is looking for include files, so you must use
    CPPFLAGS instead if you need to help 'configure' find header files.

LD_LIBRARY_PATH="?"
    'ld' uses this colon-separated list to find libraries.

LDFLAGS="?"
    Pass these flags when linking.

PATH="?"
    'configure' uses this to find programs.

=== Advanced compilation =======================================================

To run integrated regression tests, type:

    make check

To clean up build results to varying degrees, use the following make targets:

    clean
    distclean
    relclean

=== Advanced installation ======================================================

Optionally, define make variables when invoking make, including (not
exclusively):

INCLUDEDIR="?"
    Use this as the installation prefix for header files.

LIBDIR="?"
    Use this as the installation prefix for libraries.

MANDIR="?"
    Use this as the installation prefix for man pages.

CC="?"
    Use this to invoke the C compiler.

CFLAGS="?"
    Pass these flags to the compiler.

CPPFLAGS="?"
    Pass these flags to the C preprocessor.

LDFLAGS="?"
    Pass these flags when linking.

PATH="?"
    Use this to search for programs used during configuration and building.

=== Development ================================================================

If you intend to make non-trivial changes to jemalloc, use the 'autogen.sh'
script rather than 'configure'.  This re-generates 'configure', enables
configuration dependency rules, and enables re-generation of automatically
generated source files.

The build system supports using an object directory separate from the source
tree.  For example, you can create an 'obj' directory, and from within that
directory, issue configuration and build commands:

    autoconf
    mkdir obj
    cd obj
    ../configure --enable-autogen
    make