Recognising that 1 2 + 2 4 is a loop with 2 iterations the decision could be made to do it in serial.
Recognising that (i.1000000) + (i.1000000) is a loop with many iterations the decision could be made to explore doing "+" in parallel. Isn't this the type of decision that i. does for algorithm selection? On 15 February 2010 18:49, Devon McCormick <[email protected]> wrote: > Raul - yes - there's always been a lot of hand-waving magic about the > benefits of parallel processing but many a pretty ship of theory has > foundered on the cold hard rocks of fact. Until you consider a specific > problem and do the work, you can't make any claims about the benefits. > > In fact, it's easy to offer a "dis-proof of concept": parallelize > > 1 2+3 4 > > I bet any parallel version of this will lose to the non-parallel version - > there's no way the overhead cost of breaking up and re-assembling the > results of this small piece of work is less than simply doing it. > > We talked about this at the last NYCJUG and I'm glad to see it's still a > pressing topic as this will motivate me to update the wiki for February's > meeting. > > Regards, > > Devon > > On Mon, Feb 15, 2010 at 12:33 PM, Raul Miller <[email protected]> > wrote: > > > On Mon, Feb 15, 2010 at 11:00 AM, bill lam <[email protected]> wrote: > > > Apart from the startup time and memory cost, the biggest problems are > > > the need to tailor the algorithm by programmer for each for its > > > applications, synchronisation of sessions, the memory bandwidth it > > > took to transfer data between session. OTOH the low level solution is > > > transparent, J programmers will not even need to aware its existence. > > > Henry Rich had also suggested this approach if memory served me. > > > > One problem with the low level approach seems to be that, so > > far, no one wants to fund the investigative costs associated with > > this change. > > > > To my knowledge no one has even shown a "proof of concept" > > implementation for any primitive. > > > > -- > > Raul > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > > -- > Devon McCormick, CFA > ^me^ at acm. > org is my > preferred e-mail > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
