On Thu, May 19, 2016 at 01:36:29PM -0400, Christos Zoulas wrote: > You can see how FreeBSD is implementing them; it is a lot of code to do > this and would require some architectural review. The relevant files are: > > http://nxr.netbsd.org/xref/src-freebsd/lib/libthr/thread/thr_pshared.c > http://nxr.netbsd.org/xref/src-freebsd/lib/libthr/thread/thr_barrierattr.c > http://nxr.netbsd.org/xref/src-freebsd/sys/kern/kern_umtx.c > > We don't have such mutex functionality in our kernel. Implementing this > would be a GSoC project in itself.
I don't think we want to use futexes in general. I'm not even sure I care about performance for something horrible like "robust" mutexes at all. A good starting point might to just extend the existing semaphores, if necessary. Joerg
