Re: swap

[Ron Johnson <ron.l.johnson@cox.net>]

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On 05/10/07 22:11, Douglas Allan Tutty wrote:
> On Thu, May 10, 2007 at 08:14:11PM -0500, Ron Johnson wrote:
>> On 05/10/07 18:10, Douglas Allan Tutty wrote:
>> [snip]
>  
>> And if you say "make a SSD", then I say that it's still slower than
>> RAM because disk channel bandwidth is still *much* slower than
>> memory bandwidth.  Better to spend that money on extra RAM.
>>
> 
> But if the problem/program can only run on one processor, and you have
> maxxed out the memory that that processor (or the MB it's on) can
> handle...

Then you've run into an unfixable bottleneck and are SOL.

> I've been trying to find (e.g. google, ibm) information on
> supercomputers/HPC that are built to solve sequential problems and
> striking out.  Everything is on paralellization and how clusters don't
> help if you can't make it a parallel problem.  
> 
> The other tack I've been thinking is what if you could make a virtual
> computer that ran on more than one CPU/node that was _more_ powerful
> (compute, memory, whatever) than any one CPU/node.  This would be the
> direct opposite of the current virtualization of a guest being a subset
> of the host (e.g. Xen, z/VM).  The problem here is that, unlike Xen, it
> would require a true emulation rather than passing code directly to a
> processor.  
> 
> Other than your bach job, I wonder what would be an example of a current
> real-world sequential compute problem; a long-running program that
> couldn't be run in parallel on multiple nodes.

Certain weather simulations are not parallel because the subsequent
iteration is dependent on the value of the current iteration.

In fact, by definition, iterative numerical methods are serial.
http://en.wikipedia.org/wiki/Iterative_method
http://en.wikipedia.org/wiki/Newton-Raphson_method

- --
Ron Johnson, Jr.
Jefferson LA  USA

Give a man a fish, and he eats for a day.
Hit him with a fish, and he goes away for good!

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