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Date: Thu, 29 Oct 2009 04:27:21 +0800
From: W B Hacker <wbh@conducive.org>
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To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] parallel systems
Topicbox-Message-UUID: 9310989a-ead5-11e9-9d60-3106f5b1d025

Sam Watkins wrote:
>> - a factory's line can be brought to a standstill if one of its
>> elements breaks;
>
> one would hope that software elements do not break so much
>
>> - a factory 's line is at least as slow as its slowest worker
>
> a slow part of the line can be split / duplicated to use multiple workers
>
>> - if all the workers at a car factory came to work at the same time
>> they wouldn't be able to get through the door.
>
> and yet people do come to work, car factories do exist, and they are obviously
> more powerful and efficient than a whole lot of people building individually.
>
>> if the jobs aren't big enough, the workers are underutilized.
>
> That's fine, you can switch off processing units that aren't needed, or use
> them for another task.  Software systems are much more flexible than factories.
>
>> The mediators (supervisors) that keep said workers efficiently running are
>> paid more than the workers, and it can be deduced that their job is more
>> critical overall.
>
> Yes, a parallel system might need significant resources dedicated to organizing
> and optimizing the rest of the system.
>
>> also, one more thought: near 100% factory utilization only occurs when the
>> assembly steps (pipeline) and division of assembly (divide and conquer) is
>> tailored for the exact product (task/instruction/process) to be made.
>
> Yes, it is much more difficult to reconfigure a factory than a software system.
> It is easy to configure a software system for a specific task, it may even be
> reconfigured it at run time.
>
> Sam
>
>

You forget how far our best systems - capable, running flat-out, of emulating
only a short time-slice of the brain of a rodent -  lag 'nature'.

One mouse.

Let alone our our own trillion-bit-plus equivalent massively-parallel brain.
Issued one-per to each of those factory workers, BTW - and arguably utilized to
better effect on average than has been the case right here of late...

If paralellism actually scaled as well as you wish .. 'God' would be the sole
ant-queen in the known universe, she would have faster-than-light travel...

And she never would have permitted wasps to evolve - let alone dinosaurs or humans..

Didn't happen that way.

Instead, ants learned the limitations of parallelism millions of years ago, and
decided to wait for humans to evolve so we can build starships *for* them.

Clever folks, ants are. You think we are smsrter, just compare your tax bill
with theirs.

;-)

Bill