Re: [Algorithms] General purpose task parallel threading approach

[Oscar F. <os...@tr...>]

>
> >but it seems to >me< that you are attacking the problem of multiple cores
> in totally the wrong way.
> Explain. If I make things work at the same speed as a standard approach
> (when there is no or very little contention) or faster (in case of
> contention or blocking io), what is wrong here ?


Again im not saying im correct ... but you stated that you are trying to
handle the "ability to handle blocking conditions somehow".  I'm suggesting
that you don't need this to be a problem.  Maybe we are talking about the
same thing?  Maybe im just misunderstanding you?  BUT, it still seems to me
that if blocking is a problem then you are attacking the problem wrongly.


> Could you explain a bit more about your approach ? And what do you do when
> physics iteration finishes faster than rendering iteration or the other way
> around ?


If my physics system finishes early i return its thread to the thread pool
and give its thread to the object iterations.  I only ever have twice the
number of threads that there are cores in the machine
(Experimentation showed me that this is a good tradeoff between leaving the
core stalled on things like memory access and general thread throughput. I
would love to experiment on massively multi-core systems and it looks likely
i'll get a play with a 1024 core system soon to do some testing for a non
games related problem).

I dunno what more I can tell you about my approach from my last post.
Basically I am aiming to get tasks as parallel to each other as possible.  A
given task, when it finishes, has a "callback" that tells it when it next
has to bother doing any AI decisions.  Otherwise it only handles animation
and rendering of itself.  Basically I'm looking at where a stall can occur
and trying to eliminate that stall.  Currently my only stalling occurs when
I add to global lists (message list and render list).

The system seems perfectly compatible with a networking system whereby you
don't know exactly when the next update will occur.  In fact things like the
rendering and physics could be offloaded, easily, to whole other computers
if such a need ever came about.

I'm pretty crap at explaining things.  If you have any specific questions to
ask on my approach then I'll happily attempt to answer them.  I'm better at
that :)  That said, I will re-iterate, I'm not saying your solution is
wrong.  It just goes contrary to my experience and kowledge (which is
inevitably flawed).  My system will, however, port nicely to >any<
pre-emptively multi-tasking operating system which was my aim.