No description
http://www.etalabs.net/musl/
729d6368bd
testing revealed that the old implementation, while correct, was giving way too many spurious wakeups due to races changing the value of the condition futex. in a test program with 5 threads receiving broadcast signals, the number of returns from pthread_cond_wait was roughly 3 times what it should have been (2 spurious wakeups for every legitimate wakeup). moreover, the magnitude of this effect seems to grow with the number of threads. the old implementation may also have had some nasty race conditions with reuse of the cond var with a new mutex. the new implementation is based on incrementing a sequence number with each signal event. this sequence number has nothing to do with the number of threads intended to be woken; it's only used to provide a value for the futex wait to avoid deadlock. in theory there is a danger of race conditions due to the value wrapping around after 2^32 signals. it would be nice to eliminate that, if there's a way. testing showed no spurious wakeups (though they are of course possible) with the new implementation, as well as slightly improved performance. |
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| WHATSNEW | ||
musl libc - a new standard library to power a new generation of
Linux-based devices. musl is lightweight, fast, simple, free, and
strives to be correct in the sense of standards-conformance and
safety.
musl is an alternative to glibc, eglibc, uClibc, dietlibc, and klibc.
For reasons why one might prefer musl, please see the FAQ and libc
comparison chart on the project website,
http://www.etalabs.net/musl/
For installation instructions, see the INSTALL file.
Please refer to the COPYRIGHT file for details on the copyright status
of code included in musl, and the COPYING file for the license (LGPL)
under which the library as a whole is distributed.
Greetings!
As of the 0.8.0 release, musl is in _beta_ status. While some
interfaces remain incomplete or yet to be implemented, the ABI is
intended to be stable at this point, and serious efforts have been
made, using three separate test frameworks, to verify the correctness
of the implementation. Many major system-level and user-level programs
are known to work with musl, either out-of-the-box or with minor
patches to address portability errors; the main remaining applications
which definitely will not work are those which require C++ support,
which will be addressed during the 0.8 or 0.9 development series.
Included with this package is a gcc wrapper script (musl-gcc) which
allows you to build musl-linked programs using an existing gcc 4.x
toolchain on the host. There are also now at least two mini
distributions (in the form of build scripts) which provide a
self-hosting musl-based toolchain and system root: Sabotage Linux and
Bootstrap Linux. These are much better options than the wrapper script
if you wish to use dynamic linking or build packages with many library
dependencies.
The musl project is actively seeking contributors, mostly in the areas
of porting, testing, and application compatibility improvement. For
bug reports, support requests, or to get involved in development,
please visit #musl on Freenode IRC or subscribe to the musl mailing
list by sending a blank email to musl-subscribe AT lists DOT openwall
DOT com.
Thank you for using musl.
Cheers,
Rich Felker / dalias