[nylug-talk] LOWMEM vs. HIGHMEM performance advantage?

[Ruben Safir]

> 
> A lot of this has to do with the fact that paging becomes rather
> extensive and quite constrained in the i686 kernel.  The biggest issues
> with x86-64 aren't performance.  For different segments (code, heap,
> data as well as IPC, kernel entry, etc...), 48-bit virtual pointers
> (which are then normalized to 32-bit flat, assuming your program isn't
> using PAE, even if the kernel is) are already in use.  So switching to
> 48-bit flat pointers (x86-64) changes nothing in that regard.
> 
> I've said it before and I'll say it again, the system-level performance
> and considerations have nothing to do with the application-level
> structures.  Application-level developers think there is a 32-bit/4GiB
> "flat" space.  That is hardly the case at all when it actually comes to
> system-level performance.  Even 32-bit programs use 48-bit virtual
> addressing.
> 


Care to give a lecture about 32bit and 64bit arch?  Mind you, generally
I could care less about the technology except how it affects myself
and society politically, but UNDERSTANDING the technology is key
to understanding what it can do (for you and everyone else).

If your interested.  Email me off list ruben at nylxs.com

Ruben