This is a biggy. jemalloc_internal.h has been doing multiple jobs for a while
now:
- The source of system-wide definitions.
- The catch-all include file.
- The module header file for jemalloc.c
This commit splits up this functionality. The system-wide definitions
responsibility has moved to jemalloc_preamble.h. The catch-all include file is
now jemalloc_internal_includes.h. The module headers for jemalloc.c are now in
jemalloc_internal_[externs|inlines|types].h, just as they are for the other
modules.
Hyper-threaded CPUs may need a special instruction inside spin loops in
order to yield to another virtual CPU. The 'pause' instruction that is
available for x86 is not supported on Power.
Apparently the extended mnemonics like yield, mdoio, and mdoom are not
actually implemented on POWER8, although mentioned in the ISA 2.07
document. The recommended magic bits are an 'or 31,31,31'.
The new feature, opt.percpu_arena, determines thread-arena association
dynamically based CPU id. Three modes are supported: "percpu", "phycpu"
and disabled.
"percpu" uses the current core id (with help from sched_getcpu())
directly as the arena index, while "phycpu" will assign threads on the
same physical CPU to the same arena. In other words, "percpu" means # of
arenas == # of CPUs, while "phycpu" has # of arenas == 1/2 * (# of
CPUs). Note that no runtime check on whether hyper threading is enabled
is added yet.
When enabled, threads will be migrated between arenas when a CPU change
is detected. In the current design, to reduce overhead from reading CPU
id, each arena tracks the thread accessed most recently. When a new
thread comes in, we will read CPU id and update arena if necessary.
This introduces a backport of C11 atomics. It has four implementations; ranked
in order of preference, they are:
- GCC/Clang __atomic builtins
- GCC/Clang __sync builtins
- MSVC _Interlocked builtins
- C11 atomics, from <stdatomic.h>
The primary advantages are:
- Close adherence to the standard API gives us a defined memory model.
- Type safety: atomic objects are now separate types from non-atomic ones, so
that it's impossible to mix up atomic and non-atomic updates (which is
undefined behavior that compilers are starting to take advantage of).
- Efficiency: we can specify ordering for operations, avoiding fences and
atomic operations on strongly ordered architectures (example:
`atomic_write_u32(ptr, val);` involves a CAS loop, whereas
`atomic_store(ptr, val, ATOMIC_RELEASE);` is a plain store.
This diff leaves in the current atomics API (implementing them in terms of the
backport). This lets us transition uses over piecemeal.
Testing:
This is by nature hard to test. I've manually tested the first three options on
Linux on gcc by futzing with the #defines manually, on freebsd with gcc and
clang, on MSVC, and on OS X with clang. All of these were x86 machines though,
and we don't have any test infrastructure set up for non-x86 platforms.
Rather than dynamically building a table to aid per level computations,
define a constant table at compile time. Omit both high and low
insignificant bits. Use one to three tree levels, depending on the
number of significant bits.
The SDK jemalloc is built against might be not be the latest for various
reasons, but the resulting binary ought to work on newer versions of
OSX.
In order to ensure this, we need the fullest definitions possible, so
copy what we need from the latest version of malloc/malloc.h available
on opensource.apple.com.
Add the --with-lg-hugepage configure option, but automatically configure
LG_HUGEPAGE even if it isn't specified.
Add the pages_[no]huge() functions, which toggle huge page state via
madvise(..., MADV_[NO]HUGEPAGE) calls.
Convert CFLAGS/CXXFLAGS to be concatenations:
CFLAGS := CONFIGURE_CFLAGS SPECIFIED_CFLAGS EXTRA_CFLAGS
CXXFLAGS := CONFIGURE_CXXFLAGS SPECIFIED_CXXFLAGS EXTRA_CXXFLAGS
This ordering makes it possible to override the flags set by the
configure script both during and after configuration, with
CFLAGS/CXXFLAGS and EXTRA_CFLAGS/EXTRA_CXXFLAGS, respectively.
This resolves#504.
Adds cpp bindings for jemalloc, along with necessary autoconf settings.
This is mostly to add sized deallocation support, which can't be added
from C directly. Sized deallocation is ~10% microbench improvement.
* Import ax_cxx_compile_stdcxx.m4 from the autoconf repo, seems like the
easiest way to get c++14 detection.
* Adds various other changes, like CXXFLAGS, to configure.ac.
* Adds new rules to Makefile.in for src/jemalloc-cpp.cpp, and a basic
unittest.
* Both new and delete are overridden, to ensure jemalloc is used for
both.
* TODO future enhancement of avoiding extra PLT thunks for new and
delete - sdallocx and malloc are publicly exported jemalloc symbols,
using an alias would link them directly. Unfortunately, was having
trouble getting it to play nice with jemalloc's namespace support.
Testing:
Tested gcc 4.8, gcc 5, gcc 5.2, clang 4.0. Only gcc >= 5 has sized
deallocation support, verified that the rest build correctly.
Tested mac osx and Centos.
Tested --with-jemalloc-prefix and --without-export.
This resolves#202.
The core issue here is the weak linking of the symbol, and in certain
environments--for instance, using the latest Xcode (8.1) with the latest
SDK (10.12)--os_unfair_lock may resolve even though you're compiling on
a host that doesn't support it (10.11).
We can use the availability macros to circumvent this problem, and
detect that we're not compiling for a target that is going to support
them and error out at compile time. The other alternative is to do a
runtime check, but that presents issues for cross-compiling.
Some versions of Android provide a pthreads library without providing
pthread_atfork(), so in practice a separate feature test is necessary
for the latter.
Add feature tests for the MADV_FREE and MADV_DONTNEED flags to
madvise(2), so that MADV_FREE is detected and used for Linux kernel
versions 4.5 and newer. Refactor pages_purge() so that on systems which
support both flags, MADV_FREE is preferred over MADV_DONTNEED.
This resolves#387.
The raw clock variant is slow (even relative to plain CLOCK_MONOTONIC),
whereas the coarse clock variant is faster than CLOCK_MONOTONIC, but
still has resolution (~1ms) that is adequate for our purposes.
This resolves#479.
Conditionalize use of --whole-archive on the platform plus compiler,
rather than on the ABI. This fixes a regression caused by
7b24c6e557 (Use --whole-archive when
linking integration tests on MinGW.).
This reverts 13473c7c66, which was
intended to work around bootstrapping issues when linking statically.
However, this actually causes problems in various other configurations,
so this reversion may force a future fix for the underlying problem, if
it still exists.
Add missing #include <time.h>. The critical time facilities appear to
have been transitively included via unistd.h and sys/time.h, but in
principle this omission was capable of having caused
clock_gettime(CLOCK_MONOTONIC, ...) to have been overlooked in favor of
gettimeofday(), which in turn could cause spurious non-monotonic time
updates.
Refactor nstime_get() out of nstime_update() and add configure tests for
all variants.
Add CLOCK_MONOTONIC_RAW support (Linux-specific) and
mach_absolute_time() support (OS X-specific).
Do not fall back to clock_gettime(CLOCK_REALTIME, ...). This was a
fragile Linux-specific workaround, which we're unlikely to use at all
now that clock_gettime(CLOCK_MONOTONIC_RAW, ...) is supported, and if we
have no choice besides non-monotonic clocks, gettimeofday() is only
incrementally worse.
In 1167e9e, I accidentally tested je_cv_gcc_builtin_ffsl instead of
je_cv_gcc_builtin_unreachable (copy-paste error), which meant that
JEMALLOC_INTERNAL_UNREACHABLE was always getting defined as abort even if
__builtin_unreachable support was detected.
Cray is pretty warning-happy, so disable ones that aren't helpful. Each warning
has a numeric value instead of having named flags to disable specific warnings.
Disable warnings 128 and 1357.
128: Ignore unreachable code warning. Cray warns about `not_reached()` not
being reachable in a couple of places because it detects that some loops
will never terminate.
1357: Ignore warning about redefinition of malloc and friends
With this patch, Cray 8.4.0 and 8.5.1 build cleanly and pass `make check`
Cray uses -herror_on_warning instead of -Werror. Use it everywhere -Werror is
currently used for __attribute__ checks so configure actually detects they're
not supported.
Cray only supports `-M` for generating dependency files. It does not support
`-MM` or `-MT`, so don't try to use them. I just reused the existing mechanism
for turning auto-dependency generation off (`CC_MM=`), but it might be more
principled to add a configure test to check if the compiler supports `-MM` and
`-MT`, instead of manually tracking which compilers don't support those flags.
Get jemalloc building and passing `make check_unit` with cray 8.4. An inlining
bug in 8.4 results in internal errors while trying to build jemalloc. This has
already been reported and fixed for the 8.5 release.
In order to work around the inlining bug, disable gnu compatibility and limit
ipa optimizations.
I copied the msvc compiler check for cray, but note that we perform the test
even if we think we're using gcc because cray pretends to be gcc if `-hgnu`
(which is enabled by default) is used. I couldn't come up with a principled way
to check for the inlining bug, so instead I just checked compiler versions.
The build had lots of warnings I need to address and cray doesn't support -MM
or -MT for dependency tracking, so I had to do `make CC_MM=`.
Add a configure check for __builtin_unreachable instead of basing its
availability on the __GNUC__ version. On OS X using gcc (a real gcc, not the
bundled version that's just a gcc front-end) leads to a linker assertion:
https://github.com/jemalloc/jemalloc/issues/266
It turns out that this is caused by a gcc bug resulting from the use of
__builtin_unreachable():
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57438
To work around this bug, check that __builtin_unreachable() actually works at
configure time, and if it doesn't use abort() instead. The check is based on
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57438#c21.
With this `make check` passes with a homebrew installed gcc-5 and gcc-6.
The Cray compiler wrappers will often add `-lrt` to the base compiler with
`-static` linking (the default at most sites.) However, `-lrt` isn't
automatically added with `-dynamic`. This means that if jemalloc was built with
`-static`, but then used in a program with `-dynamic` jemalloc won't have
detected that librt is a dependency.
The integration and stress tests use -dynamic, which is causing undefined
references to clock_gettime().
This just adds an extra check for librt (ignoring the autoconf cache) with
`-dynamic` thrown. It also stops filtering librt from the integration tests.
With this `make check` passes for:
- PrgEnv-gnu
- PrgEnv-intel
- PrgEnv-pgi
PrgEnv-cray still needs more work (will be in a separate patch.)
Cray systems come with compiler wrappers to simplify building parallel
applications. CC is the C++ wrapper, and cc is the C wrapper.
The wrappers call the base {Cray, Intel, PGI, or GNU} compiler with vendor
specific flags. The "Programming Environment" (prgenv) that's currently loaded
determines the base compiler. e.g. compiling with gnu looks something like:
module load PrgEnv-gnu
cc hello.c
On most systems the wrappers defaults to `-static` mode, which causes them to
only look for static libraries, and not for any dynamic ones (even if the
dynamic version was explicitly listed.)
The integration and stress tests expect to be using the .so, so we have to run
the with -dynamic so that wrapper will find/use the .so.
If the OS overcommits:
- Commit all mappings in pages_map() regardless of whether the caller
requested committed memory.
- Linux-specific: Specify MAP_NORESERVE to avoid
unfortunate interactions with heuristic overcommit mode during
fork(2).
This resolves#193.
