[linux-audio-user] 2.6.15.4, realtime-lsm, jackd -R, system performance down!

[Lee Revell]

On Mon, 2006-02-13 at 03:11 +0100, fons adriaensen wrote:
> 
> For synchronisation a POSIX sema in shared memory is quite 
> fast. Alternatives are a named one or again a pipe. Didn't
> yet test condition variables in shared memory. If those work
> that would make it rather easy to make e.g. my clthreads lib's
> ITC functions work tranparently across process boundaries.
> 

Exactly, it's quite useful.  I've tested it extensively with NPTL 2.3.6
and the multiprocess and multithread versions perform identically.

One big question I have not answered yet is whether the file has to be
on a tmpfs for operations on the synchronizaion objects to be RT safe.
So far I have been putting it in /dev/shm just to be safe.

> AFAIK, putting synchronisation objects in shared memory will
> not work with LinuxThreads. But how long will they still be
> used ? Sooner or later new apps will require a 2.6 kernel,
> and the initial problems with NPTL are well in the past
> now.
> 

If this is the case I agree fully, it's too useful a feature to allow
LinuxThreads support to hold us back.

Lee