hi victor,

thanks for taking a look at the mac side!  hope you'll have a chance
to test on a multi-core machine to see how it performs!

steven

On 4/4/07, Victor Lazzarini <victor.lazzarini@nuim.ie> wrote:
> well, it appears that the barrier code is OK for
> the Mac as it's basic pthread-based. So I have tentatively
> committed it as well. Will need testing, but it should
> work as it does on Linux.
>
> Now we just need to do the same for Win3-threads.
>
> Victor
>
> >
> > Hi All,
> >
> > I've just checked into CVS an initial attempt at getting
> > csound multithreaded.  John and I had talked a little at
> > the LAC about starting to move towards taking advantage of
> > multicore systems.  The implementation uses some code for
> > thread barriers that John sent me to use as a reference
> > and currently is implemented on Linux and has stubs there
> > for Mac and Windows (in threads.c).  While at LAC and
> > thinking about how to multithread, I got to thinking about
> > the processing order and semantics of that.  To preserve
> > the same exact order of processing as the single-threaded
> > version, I figured for an initial implementation to do
> > that is to basically have a thread pool and process each
> > set of instrument instances one at a time, i.e. processing
> > all of instr 1, then instr 2, etc.  kperf was changed when
> > --num-threads=2 or more to use barriers to call the worker
> > threads and wait on a barrier for them to finish. For code
> > in instruments which may cause race conditions, a set of
> > mutex opcodes were written: mutex_lock, mutex_unlock,
> > mutex_locki, and mutex_unlocki.  I'm not sure the i-rate
> > versions are necessary though as i-time still processes
> > all in a single thread, so those might be unnecessary.
> >
> > The strategy is a bit naive and inefficient, though I
> > don't know really what the performance is like as I only
> > have a single core machine.  I'd be very interested to
> > know how the performance is like on a multi-core machine.
> >
> > Also, right now I find that using multiple threads can
> > yield segfaults.  I haven't had much time to look at this
> > as I've been away doing some work and only doing this in
> > the little spare free time i have at the moment, and
> > probably won't have much free time for another couple
> > weeks.
> >
> > I don't expect this code and strategy to be optimal in any
> > way or that it will yield any performance benefit in the
> > end, but I thought it would be worth it to try out with a
> > pretty conservative strategy with explicit user input for
> > mutex locking, just to have some place to start from.
> > It'd be great to get some other eyes on this code and
> > thoughts on how to improve it.
> >
> > Thanks!
> > steven
> >
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