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Posted to users@tomcat.apache.org by Dave <ja...@yahoo.com> on 2008/02/25 13:51:09 UTC
OT: java memory question -Xmx2048m
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
---------------------------------
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Re: OT: java memory question -Xmx2048m
Posted by "Roland Brassous (SILOGIC)" <ro...@silogic.fr>.
Hi everyOne
From adobe Faq
On 32-bit processor machines, the largest contiguous memory address
space the operating system can allocate to a process is 1.8GB. Because
of this, the maximum heap size can only be set up to 1.8GB. On 64-bit
processor machines, the 1.8 GB limit does not apply, as 64-bit processor
machines have a larger memory address space.
regards
Roland
Dave a écrit :
> 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.
>
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Re: OT: java memory question -Xmx2048m
Posted by Mikolaj Rydzewski <mi...@ceti.pl>.
Dave wrote:
> Our Linux(FC) machine has 8G physical memory and 12G swap size.
Happy swapping ;-)
--
Mikolaj Rydzewski <mi...@ceti.pl>
Re: OT: java memory question -Xmx2048m
Posted by Alan Chaney <al...@compulsivecreative.com>.
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
Regards
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 <de...@oma.be> 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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Re: OT: java memory question -Xmx2048m
Posted by Dave <ja...@yahoo.com>.
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 <de...@oma.be> 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 :)
--
http://www.devlog.be (a belgian developer's logs)
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---------------------------------
Never miss a thing. Make Yahoo your homepage.
Re: OT: java memory question -Xmx2048m
Posted by David Delbecq <de...@oma.be>.
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 :)
--
http://www.devlog.be (a belgian developer's logs)
---------------------------------------------------------------------
To start a new topic, e-mail: users@tomcat.apache.org
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