[PD-dev] per-thread storage in Pd in support of pdlib - discussion?

[Charles Henry]

On 2/11/12, Mathieu Bouchard <matju at artengine.ca> wrote:
> Le 2012-01-26 à 14:45:00, Charles Henry a écrit :
>
>> When talking about cluster computing, I had someone once ask: "Is that a
>> case where the whole is greater than the sum of its parts?" "It's less.
>> Always less."
>
> Depends on how you count it. You may also see it as a bunch of computers
> in which 0 computer can do task T in time N, but they can join together to
> form 1 (or more) computer(s) that can do task T in time N or less. In that
> sense, it's infinitely more powerful. This way of seeing it is much more
> important in realtime apps than in batch-compute-over-the-weekend apps.
>
> It's like how one ninja turtle alone can't beat a certain evil monster,
> but with teamwork, they can. ;)

You just always lose on efficiency whenever you use several threads or
multiple nodes.  Best case is "less than or equal" to the sum of its
parts, and equal only when all the things you want to do are
independent.

It's easy to see that potential for doing fast calculations building a
cluster... and then get disappointed to see how much of it gets
wasted.  Look at that: a user just put 64 threads on one node and it
spends all its time switching contexts.  erm... the /home filesystem
is where one user was just trying to write 500 output files at once,
and no one has been able to login for hours.

I'll go back to wasting my time, and see if I can make it parallel ;)