[Beowulf] Moores Law is dying
Joe Landman
landman at scalableinformatics.com
Tue Apr 14 14:11:53 PDT 2009
Jon Forrest wrote:
>> that compilers will never try to unroll code at that level, even when
>> enormous memory systems are commonplace?
>
> Again, the enormous memory systems you mention consist mostly
> of enormous amounts of data, not text.
>
... so I see you have never used an interprocedural analysis (-ipa)
switch :)
Allows you do do things like, I dunno, inline one whole routine inside
another ...
Usually leads to much larger program text sizes.
This said, I have seen very large programs from RISC days hitting well
more than 1 GB of text. I haven't played with any recently though.
[...]
>> and "the program" being run on a multitasking
>> operating system is the union of all "sub" programs being run on the
>> system, with or without shared libraries (sharing is expensive in
>> performance, remember -- we do it to save memory because it is a scarce
>> resource).
>
> Why is sharing expensive in performance? It might take a little
> overhead to setup and manage, but why is having multiple virtual
> addresses map to the same physical memory expensive?
Contention. Memory hot spots. Been there, done that. We are about to
do this all over again (collectively).
--
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
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