Hi Michael,

To run with multiple threads, use --num-threads=x  where x is the
number of threads to use (probably start off with x = num cores and
try out different values there).  Not setting --num-threads defaults
to 1 and therefore defaults to using the old scheduler and kperf.  For
the ORC, we do not currently have support for any goto's, including
any if's.  At least, not without using the mutex opcodes
(http://www.nabble.com/Mutlithreaded-Csound-to9823048.html#a9823048).
The code for the mutex ops are in Opcodes/mutexops.c.  I think you
just give a mutex number to lock on, and the mutex opcodes will create
a mutex and lock and unlock on that mutex.  You should also be able to
do multiple locks and unlocks.

I would suggest for just testing purposes now for performance to try
out with very simple orchestras.

Besides the problems with ifs/gotos, we need to see what other code is
referencing CURREVT and any other "global" variable that is held in
the Csound struct.  If we are going to pursue this seriously, I think
we should aim to remove fields from the Csound struct that are global
like this and break API compatibility, or at minimum, disable locally
and remove all references and reenable to check in with a comment that
it no longer should be used, if we want to maintain API compatibility.
 I'm for breaking API compatibility in this regard as I wouldn't want
anyone in the future to try to use these values, but don't see a
problem to stick with compatibility for now.

Also, the work partition is done on each kperf which was done to work
with the data structure that events are currently stored in (a long
linked-list, sorted by instr num).  I think we would get benefit to
instead do the work partition when events are added to the work queue
and to pre-separate the work into different queues.  That way kperf
won't have to repartition every pass but instead just do the work.

Otherwise, doing a CVS update now and will try it out here on WinXP!
steven


On Thu, May 29, 2008 at 10:17 AM, Michael Gogins <gogins@pipeline.com> wrote:
> Now that I have replaced Windows threading with Posix threads (pthreads) in the Windows build of Csound, and a cursory test says it still works, I have questions.
>
> How do I enable the multi-threading option when rendering with Csound?
>
> Is there anything special I have to do, or not do, in my orc file?
>
> Regards,
> Mike
>
>
>
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