Re: Linux scalability question

[Steven Pritchard <steve@silug.org>]

Robert Threet said:
> A recent SCO PR blurb said that unlike Unixware, Linux
> was limited to 2GB of memory and a 2GB file size.

That can't possibly be recent.  SCO is basically owned by Caldera now.
Surely they aren't still FUDing Linux.

It's somewhat true though...  2.2.x kernels (unpatched) can only use
2GB of memory, and have a 2GB file size limit.  Patched 2.2.x kernels
support 4GB of memory (IIRC) and 64-bit file offsets, meaning the
upper limit on file size is insanely large.  2.4.x (will) do both out
of the box.

> Is this a reference to the Intel version of Linux?

Actually, the limitations are true on all 32-bit architectures that
Linux runs on.  I'm not sure how the 2.2.x bigmem and LFS (large
files) patches affect non-x86 architectures.

> I mean, wouldn't the 64 bit Alpha or StrongArm RISC
> version of Linux automatically overcome these issues?

StrongARM is a 32-bit processor, so it has the same limitations.
You're right though...  If you run Linux on 64-bit platforms like
Alpha and UltraSPARC, you don't have these limitations.  That said,
there are some problems in 2.2.x with large memory situations even on
64-bit platforms because of some ISA and PCI brain damage.  2.4.x
works around all of that.

Still, if you want to run Linux on a Really Big Box today, you can.
Easily.

Oh, BTW, SGI even has ccNUMA working on 2.4.x.  :-)  (I don't know if
the patches are generally available yet, but it's still pretty
cool...)

Steve
-- 
steve@silug.org           | Linux Users of Central Illinois
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Steven Pritchard          | http://www.luci.org/ for more info
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