8G RAM in 32bit platform

[David Carter]

On Fri, 13 Jul 2007, Patrick T. Tsang wrote:

> We will start up the mail server with 4G RAM.
> As I know the 32bits cannot handle RAM more than 3.2G.
>
> The client plans to upgrade the RAM to 8G in coming years.
> Can the 64bits platform is the only solution to it?

You don't say which CPU or operating system you are using.

The Linux bigsmp kernel supports PAE extensions on IA32 platforms: all 8 
GBytes will be available as buffer cache, which is what matters to Cyrus.

64 bit pointers don't really do anything: no single process in Cyrus needs 
2 GBytes of address space. 64 bit integer arithmetic would be a slight 
benefit for quota arithmetic (unsigned long long). However my systems 
spend about 2% of their time in user CPU state according to vmstat. You 
really aren't going to notice on any modern Intel/AMD CPU.

-- 
David Carter                             Email: David.Carter at ucs.cam.ac.uk
University Computing Service,            Phone: (01223) 334502
New Museums Site, Pembroke Street,       Fax:   (01223) 334679
Cambridge UK. CB2 3QH.