From: MenTaLguY <mental@...>
Date: 2007-10-04T02:49:15+09:00
Subject: Re: Recent Criticism about Ruby (Scalability, etc.)

On Thu, 4 Oct 2007 02:39:28 +0900, MenTaLguY <mental@rydia.net> wrote:
> On Thu, 4 Oct 2007 01:42:22 +0900, Chad Perrin <perrin@apotheon.com> wrote:
>>> > That's true. However, very roughly, compute resource can scale about
>>> > linearly with compute requirement.
>>>
>>> What about Amdahl's law?
>>
>> What about it?  Unless you're writing software that doesn't scale with
>> the hardware, more hardware means linear scaling, assuming bandwidth
>> upgrades.  If bandwidth upgrades top out, you've got a bottleneck no
>> amount of hardware purchasing or programmer time will ever solve.
> 
> Amdahl's law is relevant because most software _can't_ be written to
> scale entirely linearly with the hardware, because most computational
> problems are limited in the amount of parallelism they admit.  You may
> have been fortunate enough to have been presented with a lot of
> embarrassingly parallel problems to solve, but that isn't the norm.

Actually, this is not entirely true.  Amdahl's law only applies to
optimizing a fixed workload.  I need to rethink this argument.

-mental