Re: 10 GB in Opteron machine

[Stephen Frost <sfrost@snowman.net>]

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* Jakob Oestergaard (jakob@unthought.net) wrote:
> This is really the clever way to run a 64-bit system - 99% of what is
> commonly run on most systems only gains overhead from the 64-bit address
> space - tools like postfix, cron, syslog, apache, ... will not gain from
> being native 64-bit.

For most 64-bit systems, sure.  For amd64 it's a little different
because there are additional changes to the architecture (as compared to
ia32/x86) which can more than make up for the difference for many
applications.  Then there's also things like encryption (postfix/tls,
apache/ssl, etc) which can benefit greatly from better handling of
64bit (and larger) types.

So, basically, it's not nearly so clear-cut as you portray it. :)

> Solaris has done this for ages - maintaining a mostly 32-bit user space,
> a 64-bit kernel, and then allowing for certain memory intensive
> applications to run natively 64-bit.

The differences between a 64bit sparc chip in 32bit and 64bit are quite
a bit less than the differences between an amd64 chip in 32bit and
64bit.  Thus, this makes alot more sense for sparc.

> It's a nice way to run a Linux based system too, IMO.

Perhaps on sparc or mips; it's much less clear-cut on amd64.

	Stephen

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