Groups > comp.lang.java.programmer > #20516

Re: 32G ram

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From	Nigel Wade <nmw@ion.le.ac.uk>
Newsgroups	comp.lang.java.programmer
Subject	Re: 32G ram
Date	Wed, 19 Dec 2012 11:28:50 +0000
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On 19/12/12 01:22, Arne Vajhøj wrote:
> On 12/18/2012 4:19 AM, Nigel Wade wrote:
>> On 17/12/12 08:39, Donkey Hottie wrote:
>>> 17.12.2012 05:09, Arne Vajhøj kirjoitti:
>>>> On 12/16/2012 10:05 PM, mcheung63@gmail.com wrote:
>>>>> i got 32GB ram, why i can't -Xmx2G, it got an error "Could not
>>>>> create the Java Virtual Machine"
>>>>>
>>>>> /root>free -m
>>>>> total used free shared buffers
>>>>> cached
>>>>> Mem: 32387 16973 15413 0 243
>>>>> 11906
>>>>> -/+ buffers/cache: 4823 27563
>>>>> Swap: 1906 0 1906
>>>>> /root>uname -a
>>>>> Linux localhost.localdomain 3.6.9-2.fc17.i686.PAE #1 SMP Tue Dec 4
>>>>> 14:15:28 UTC 2012 i686 i686 i386 GNU/Linux
>>>>
>>>> 32 bit or 64 bit Java?
>>>
>>> Apparently 32 bit, as the i686 OS is 32 bit PAE too.
>>
>> 32bit Java on 32bit Linux should allow an application of up to 4GB. How
>> much can of that can be allocated to the heap depends on the particular
>> application. I've allocated more than 2G to heap on a 32bit Linux
>> system, see this old thread on Google Groups:
>> https://groups.google.com/forum/?hl=en-GB&fromgroups=#!topic/comp.lang.java.programmer/iGr3bxL9ZCA
>>
>
> 32 bit Java can in theory use up to 3 GB on 32 bit OS on x86 if the
> border between process and system is changed (/3GB). But on Windows
> JRocket is supposedly the only Java that can do it.

Sorry, yes, I had confused myself by thinking about PAE.  For normal 
32bit systems this is true.

>
> 32 bit Java can never use 4 GB on 32 bit OS on x86, because that
> does not leave any address space for the OS.

However, the OP is using a PAE kernel. That should theoretically allow a 
per-process limit of 4GB. I've never had the chance to use PAE kernels 
on PAE supported hardware, but IIRC that's what PAE is for, isn't it?

-- 
Nigel Wade

Thread

32G ram mcheung63@gmail.com - 2012-12-16 19:05 -0800
  Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-16 22:09 -0500
    Re: 32G ram Donkey Hottie <donkey@fredriksson.dy.fi> - 2012-12-17 10:39 +0200
      Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-17 17:37 -0500
        Re: 32G ram Lew <lewbloch@gmail.com> - 2012-12-17 15:38 -0800
      Re: 32G ram Nigel Wade <nmw@ion.le.ac.uk> - 2012-12-18 09:19 +0000
        Re: 32G ram BGB <cr88192@hotmail.com> - 2012-12-18 14:57 -0600
        Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-18 20:22 -0500
          Re: 32G ram Nigel Wade <nmw@ion.le.ac.uk> - 2012-12-19 11:28 +0000
            Re: 32G ram BGB <cr88192@hotmail.com> - 2012-12-19 07:19 -0600
            Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 09:17 -0500
              Re: 32G ram Tim Slattery <Slattery_T@bls.gov> - 2012-12-19 12:51 -0500
                Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 13:20 -0500
                Re: 32G ram BGB <cr88192@hotmail.com> - 2012-12-19 12:40 -0600
                Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-19 13:56 -0500
  Re: 32G ram Roedy Green <see_website@mindprod.com.invalid> - 2012-12-17 00:31 -0800
    Re: 32G ram Arne Vajhøj <arne@vajhoej.dk> - 2012-12-17 20:37 -0500
  Re: 32G ram Sven Köhler <remove-sven.koehler@gmail.com> - 2012-12-19 20:40 +0100

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