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From Alan Chaney <>
Subject Re: OT: java memory question -Xmx2048m
Date Mon, 25 Feb 2008 16:53:33 GMT
For some reason Linux always calls 64 bit OSes 'AMD' - in fact, the sun 
64 bit AMD version works fine on modern 64 bit Intel CPUs. The confusion 
comes because there was an older 64 bit design from Intel called the 
'Itanium' which was intended for servers and had a completely different 
instruction set. The Xeon family and the E64 family are all compatible 
with the 'AMD' 64 bit JVM

You say DELL 2590 - do you mean DELL 2950? The 2950 is takes Intel Xeon 
processors which will work with the so-called 'AMD' JVM.

Hope that helps


Alan Chaney

Dave wrote:
> I installed Linux FC6 64-bit on the machine DELL 2590(I think it is INTEL type CPU).
But JVM 64-bit is only available for AMD and SPARC.  Is the SUN not support INTEL?
>   Thanks, Dave
> David Delbecq <> wrote:
>   En l'instant précis du 25/02/08 13:51, Dave s'exprimait en ces termes:
>> Our Linux(FC) machine has 8G physical memory and 12G swap size. I am using JDK 1.5.
I tried to set the Java option -Xmx to set max heap size for best performance, the allowed
max heap size is 2048M . Does that mean that the JVM can not use all the physical memory (8G)
? Thanks.
>> Dave
>> ---------------------------------
>> Never miss a thing. Make Yahoo your homepage.
> The maximum memory the JVM can use depends on the maximum size of 
> continuous memory segment the OS you run on allows you to reserve.
> On 32 bits linux, it's about 2G (that is 4G minus memory area reserved 
> for kernel, minus memory area used by libraries minus other thingies jvm 
> might use). To get more you will need a 64bits JVM + a 64 bits OS. Note 
> it's a limitation of hardware architecture and OS more than a limitation 
> of JVM.
> PS: if you plan to swap-out 12G of datas, i hope your disks are fast :)

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