Hi all,

But can you use a 64bit kernel on a 32bit processor?
I was assuming you couldn't however I'm happy to be corrected.

Ben


 

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Glen Turner
Sent: Thursday, 26 July 2007 5:16 PM
To: slug
Subject: RE: [SLUG] reported memory and actual memory

On Wed, 2007-07-25 at 16:06 +0800, [EMAIL PROTECTED] wrote:
> 32 bit machines can't use more than 4G. Bigmem kernels fiddle and go 
> partway but to use more than 4G use 64 bit!

More specifically, the bigmem 32-bit kernel uses PAE to use RAM greater
than 4GB.

The bad news is that this doesn't increase the size of lowmem (a
complicated topic, but basically the memory that can be used for disk
I/O and networking). For some workloads this can be a problem because of
the kernel's tendency to fragment lowmem (eg, backup servers are prone
to this).

That's the reason why it is better to use a 64-bit kernel. Of course,
that has flow-on effects if you use bespoke or binary applications since
you will need to recompile. Also, it can have an effect on your capacity
planning -- 64bit applications usually need 25% more RAM.  Of course,
with as much RAM as you have you might be amply provisioned with RAM
anyway.

--
 Glen Turner

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