[erlang-questions] Parallel Shootout & a style question

Benjamin Tolputt <>
Thu Sep 4 02:23:25 CEST 2008


Mats Cronqvist wrote:
> Benjamin Tolputt wrote:
>>  The issue is that taking the direction you suggest *right now* will
>> have
>> the effect of making Erlang slower for most tasks on most platforms it
>> is currently deployed on. 
>  Will it? I doubt it would make a realistic application (e.g. a phone
> switch) significantly slower even on single core HW. Perhaps you're
> aware of some measurement that would prove me wrong?

I could not answer that question in any convincing way to you as:

    * You define "realistic applications" to be something I do not use
      Erlang for
    * You use the words "significantly slower", yet discard 10% as being
      insignificant to those unwilling to upgrade existing hardware..

In other words, I cannot argue with you when we cannot agree on the
basic definitions of "realistic" and "significant". We'd be lost in a
"semantic argument" - one I would rather avoid. I think, however, that
you agree making everything "parallel" will slow things down on
single/dual core systems even if you find my applications unrealistic
and/or the speed decrease insignificant.

>  regardless, the only way to surf on Moore's Law is to parallelize. 

I'm not arguing that this is the case. However, not all applications
Erlang is used for have "surfing Moore's Law" as a fundamental reason
for it's use. I know my choice was only partially influenced by this factor.

> parallelizing should be made under the hood. and, frankly, i'm
> unimpressed by people who care about 10% effects on CPU time but are
> unwilling to move to multicore HW.

And thankfully, you are not the person(s) I am appealing to when writing
these messages to the mailing list. I am sure I am not the only
developer that has to deploy Erlang applications on existing hardware
setups (you know, those single/dual core ones we paid good money for not
that long ago). Having to tell the bean-counters that I need to purchase
new "many-core" systems because the platform we're developing in has
dropped performance 10% (without our code changing), is not something
any developer relishes.

--Ben



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