[Beowulf] Moores Law is dying

Joe Landman landman at scalableinformatics.com
Tue Apr 14 18:22:40 EDT 2009


Jon Forrest wrote:

> But this wouldn't happen in the scenarios you describe
> because text is read-only. There would be no updaters or writers
> or any kind of contention. The text pages would have to get filled

Ok, lets assume you have a table in the text, that every thread is using 
to dereference.  Sure it can go in the data section, but some compilers 
(old SGI) could leave it in the text area for faster access.

Same thing with contention.  Read contention is harder to diagnose than 
write contention, as you don't get the cache line update from the writes 
triggering the associated counters, so this is a bit more subtle.  But 
the effect is there.

[...]

>> I know you might postulate that 32 bit text is effectively the CS 
>> equivalent of "C" in physics ... you may approach it asymptotically, 
>> but never actually get there ... but unlike in physics, there isn't 
>> really an underlying reason why you might not get there.
> 
> The underlying reason in this case is complexity.

So you are posulating that complexity scales as Nbytes of text?

> 
> Jon
> 


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