Zach Deedler wrote: > This site explains it all: > http://en.wikipedia.org/wiki/64-bit > > 2^32 = 4GB > 2^64 = 17,179,869,184GB or 16 exabytes > (I was wrong before). > Actually this depends on whether the CPU you're using can really address this much memory - I seem to recall that AMD cpu's are limited to 48-bit physical addresses.
> Some operating systems reserve portions of process address space for OS use, > effectively reducing the total address space available for mapping memory > for user programs. For instance, Windows XP DLLs and userland OS components > are mapped into each process's address space, leaving only 2 to 3.8 GB > (depending on the settings) address space available, even if the computer > has 4 GB of RAM. This restriction is not present in 64-bit Windows. > > Not sure what linux does. But, you can't get past the 4GB ceiling for a > process on a 32-bit OS. Last I checked, Linux allowed 3GB/process of user-addressable memory running a 32-bit kernel. Another advantage that you can get from running in 64-bit mode, at least with x86-64 cpu's, is the use of twice as many processor registers (all 64-bits wide). This can sometimes speed up programs if you use the right optimization flags. Don > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Robert > Balfour > Sent: Thursday, November 29, 2007 9:54 AM > To: OpenSceneGraph Users > Subject: Re: [osg-users] 64-bit OSG > > Gordon Tomlinson wrote: > >>Note on 32 bit even though the system may let you get to 3gb of memory > > seen > >>Your addressable memory space per process will be limited to around 1.8gb > > on > >>a 32bit system >> > > > Why is that? And is that per process, or per thread? > > > Bob. -- "A government that is big enough to give you all you want is big enough to take it all away." -- Barry Goldwater +----------------------------------------+ | Don Tidrow | | Visualization Software Engineer | | SAIC | | ph: 703-253-1094 | +----------------------------------------+ _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
