[9fans] NUMA

[tlaronde@polynum.com]

This a generic question and not peculiar to plan9.

In my main software (KerGIS), there are often two versions of the data.
One version is saved, in a filesystem, in a portable format (size of int
and float defined; endianness defined) so that the data can be served by
a fileserver and used by whatever kind of CPU.

In memory, the structures used to manage processing, and the data
itself, are as expected by the CPU as a result of the C types used
and the compilation.

Writing down an explanation about the differences between the on file
saved version, and the runtime structures, I wrote that portable was for
sharing between whatever CPU architectures, while the in memory was
fitting a particular architecture because the memory is tightly coupled
to the cores and not shar... Oups! Hence the question.

In my limited view and knowledge on this subject, an elemetary CPU
(an atom) is not only a processing unit, but also the main memory
tightly coupled with it by some main bus. I guess that the main
NUMA _hardware_ are composed of same architecture cores, and there
is no mix with different cores architecture. But there are also
"software" NUMA.  Even if I don't plan at all to change this runtime
"localization"---so the question is a theoretical one---are there
systems designed for migrating portions of main memory between different
architecture cores?

Thanks for any lesson.
--
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                      http://www.kergis.com/
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