Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!storethat.news.telefonica.de!telefonica.de!news-1.dfn.de!news.dfn.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Nigel Wade Newsgroups: comp.lang.java.programmer Subject: Re: 32G ram Date: Wed, 19 Dec 2012 11:28:50 +0000 Lines: 49 Message-ID: References: <7f80256a-03d0-4ecd-b20f-164547e4f573@googlegroups.com> <50ce8cd7$0$287$14726298@news.sunsite.dk> <50d116bd$0$281$14726298@news.sunsite.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Trace: individual.net JlS3nGD0aoskio6UUMUZZwx1RVtnKL3pWKfqQd+12msCEPv3AYbiGm2d9pzH42bdFb Cancel-Lock: sha1:dKf/0tj2Txbwr4k5i1ycYr2+kqQ= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120421 Thunderbird/12.0 In-Reply-To: <50d116bd$0$281$14726298@news.sunsite.dk> Xref: csiph.com comp.lang.java.programmer:20516 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