3609f65de3
If pthread_create() is linked into the binary, then the cosmo runtime will create an independent dlmalloc arena for each core. Whenever the malloc() function is used it will index `g_heaps[sched_getcpu() / 2]` to find the arena with the greatest hyperthread / numa locality. This may be configured via an environment variable. For example if you say `export COSMOPOLITAN_HEAP_COUNT=1` then you can restore the old ways. Your process may be configured to have anywhere between 1 - 128 heaps We need this revision because it makes multithreaded C++ applications faster. For example, an HTTP server I'm working on that makes extreme use of the STL went from 16k to 2000k requests per second, after this change was made. To understand why, try out the malloc_test benchmark which calls malloc() + realloc() in a loop across many threads, which sees a a 250x improvement in process clock time and 200x on wall time The tradeoff is this adds ~25ns of latency to individual malloc calls compared to MODE=tiny, once the cosmo runtime has transitioned into a fully multi-threaded state. If you don't need malloc() to be scalable then cosmo provides many options for you. For starters the heap count variable above can be set to put the process back in single heap mode plus you can go even faster still, if you include tinymalloc.inc like many of the programs in tool/build/.. are already doing since that'll shave tens of kb off your binary footprint too. Theres also MODE=tiny which is configured to use just 1 plain old dlmalloc arena by default Another tradeoff is we need more memory now (except in MODE=tiny), to track the provenance of memory allocation. This is so allocations can be freely shared across threads, and because OSes can reschedule code to different CPUs at any time. |
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|---|---|---|
| .. | ||
| calls | ||
| crt | ||
| dlopen | ||
| elf | ||
| fmt | ||
| integral | ||
| intrin | ||
| irq | ||
| isystem | ||
| log | ||
| mem | ||
| nexgen32e | ||
| nt | ||
| proc | ||
| runtime | ||
| sock | ||
| stdio | ||
| str | ||
| sysv | ||
| testlib | ||
| thread | ||
| tinymath | ||
| vga | ||
| x | ||
| ar.h | ||
| assert.h | ||
| atomic.h | ||
| BUILD.mk | ||
| complex.h | ||
| cosmo.h | ||
| cxxabi.h | ||
| dce.h | ||
| dos.internal.h | ||
| empty.s | ||
| errno.h | ||
| imag.internal.h | ||
| inttypes.h | ||
| iso646.internal.h | ||
| limits.h | ||
| literal.h | ||
| mach.internal.h | ||
| macho.internal.h | ||
| macros.internal.h | ||
| math.h | ||
| paths.h | ||
| README.md | ||
| serialize.h | ||
| stdalign.internal.h | ||
| stdbool.h | ||
| stdckdint.h | ||
| stdlib.h | ||
| temp.h | ||
| testlib-test.txt | ||
| time.h | ||
| type2str.h | ||
| unistd.h | ||
| utime.h | ||
| zip.internal.h | ||
Cosmopolitan Standard Library
This directory defines static archives defining functions, like
printf(), mmap(), win32, etc. Please note that the Cosmopolitan
build configuration doesn't link any C/C++ library dependencies
by default, so you still have the flexibility to choose the one
provided by your system. If you'd prefer Cosmopolitan, just add
$(LIBC) and $(CRT) to your linker arguments.
Your library is compromised of many bite-sized static archives. We use the checkdeps tool to guarantee that the contents of the archives are organized in a logical way that's easy to use with or without our makefile infrastructure, since there's no cyclic dependencies.
The Cosmopolitan Library exports only the most stable canonical
system calls for all supported operating systems, regardless of
which platform is used for compilation. We polyfill many of the
APIs, e.g. read(), write() so they work consistently everywhere
while other apis, e.g. CreateWindowEx(), might only work on one
platform, in which case they become no-op functions on others.
Cosmopolitan polyfill wrappers will usually use the dollar sign naming convention, so they may be bypassed when necessary. This same convention is used when multiple implementations of string library and other performance-critical function are provided to allow Cosmopolitan to go fast on both old and newer computers.
We take an approach to configuration that relies heavily on the
compiler's dead code elimination pass (libc/dce.h). Most of the
code is written so that, for example, folks not wanting support
for OpenBSD can flip a bit in SUPPORT_VECTOR and that code will
be omitted from the build. The same is true for builds that are
tuned using -march=native which effectively asks the library to
not include runtime support hooks for x86 processors older than
what you use.
Please note that, unlike Cygwin or MinGW, Cosmopolitan does not achieve broad support by bolting on a POSIX emulation layer. We do nothing more than (in most cases) stateless API translations that get you 90% of the way there in a fast lightweight manner. We therefore can't address some of the subtle differences, such as the nuances of absolute paths on Windows. Our approach could be compared to something more along the lines of, "the Russians just used a pencil to write in space", versus spending millions researching a pen like NASA.