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e6e8213244
the entire intent of using madvise/MADV_FREE on freed slots is to improve system performance by avoiding evicting cache of useful data, or swapping useless data to disk, by marking any whole pages in the freed slot as discardable by the kernel. in particular, unlike unmapping the memory or replacing it with a PROT_NONE region, use of MADV_FREE does not make any difference to memory accounting for commit charge purposes, and so does not increase the memory available to other processes in a non-overcommitted environment. however, various measurements have shown that inordinate amounts of time are spent performing madvise syscalls in processes which frequently allocate and free medium sized objects in the size range roughly between PAGESIZE and MMAP_THRESHOLD, to the point that the net effect is almost surely significant performance degredation. so, turn it off. the code, which has some nontrivial logic for efficiently determining whether there is a whole-page range to apply madvise to, is left in place so that it can easily be re-enabled if desired, or later tuned to only apply to certain sizes or to use additional heuristics. |
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| src | ||
| tools | ||
| .gitignore | ||
| .mailmap | ||
| configure | ||
| COPYRIGHT | ||
| dynamic.list | ||
| INSTALL | ||
| Makefile | ||
| README | ||
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| WHATSNEW | ||
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/