[uClinux-dev] Threading and synchronization questions

Mike Frysinger vapier at gentoo.org
Sat Feb 28 15:10:44 EST 2009


On Saturday 28 February 2009 15:07:05 Jamie Lokier wrote:
> Michael Schnell wrote:
> > >4) Can pthread mutexes be used across vfork/exec sub-processes?
> > >In documentation to pthreads they say that the pthread_mutex can be
> > >used to synchronize threads but not processes. But I see no difference
> > >between thread and process in uClinux. What am I missing?
> >
> > To do threads you should use the pthread library. So you don't bother
> > about (v)fork-ing the threads. pthreadlib also provides the thread-mutex
> > methods and supposedly will use FUTEX (fast user space Mutex) instead of
> > mutex, which is a lot faster if the architecture provides appropriate
> > support.
>
> It only uses FUTEX if the pthread library is NPTL, and I don't think
> that's available for ARM no-MMU at the moment.

i believe David Howells has down a lot of work to get futex's working on no-
mmu.  but that doesnt mean the syscall has been added and people have actually 
tested it yet ...
-mike
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