Gary Kjos
garykjos at gmail.com
Thu Aug 31 09:51:31 CDT 2006
http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx http://support.microsoft.com/kb/108393/EN-US/ http://support.microsoft.com/kb/291988/ http://forums.amd.com/lofiversion/index.php/t52417.html On 8/31/06, JWColby <jwcolby at colbyconsulting.com> wrote: > Is anyone using a machine with more than two gig of Ram? I am reading > things about doing this and there seems to be a lot of confusion on the > matter. Much of the confusion seems to come from the fact that until the 64 > bit versions of the X86 processors, the "internals" of the processor were > all 32 bits which limited direct generation of addresses to 4 gig. All of > my machines are 64 bit (AMD) processors so theoretically they can use more > than 4 gig but how? > > Everyone seems to agree that in XP32, only 4 gig is available to work with > and that things like video cards and other "machine stuff" eats into that. > Thus regardless of anything, you will end up with less than 4 gig due to > that, perhaps as little as 3.25 gig. After that, confusion reigns, at least > in my mind. > > Understand that I am discussing Windows XP 32 specifically, although anyone > is welcome to chip in what they "know" regarding other windows versions as > long as they specify what version they are discussing. > > The next thing that is discussed is that the OS itself reserves 2 gig for > itself (which includes the video etc AFAICT), leaving up to 2 gig for EACH > APPLICATION, implying that any application can have / use up to 2 gig. > > Some claim that if you have 4 gig, the swap file won't be used since that is > part of the 4 gig available. It seems illogical since each application can > use up to 2 gig. However I have created a separate partition to hold my > swap file and tried to create one of 6 gig and Windows refused, limiting the > size of the swap file to 4 gig. > > So I am trying to figure out what the reality is. If a machine has 4 gig > physical ram, and "machine stuff" uses (for argument's sake) .75 gig, is the > .75 gig of physical ram simply unused? Is it used by the OS for buffers? > What about the swap file? If you have a 4 gig swap file, would you have > 7.25 "total available memory" for Windows use? Does this indeed then limit > the APPLICATIONS to 5.25 gig of "total" memory and 2 gig of physical memory? > And what happens if you manage to get (for the sake of argument) 8 gig > stuffed into a machine. Some motherboards claim to handle that much but can > Windows XP 32 actually use it? > > Can Windows XP 64? If you need this much memory is Windows XP 64 a way to > get at the memory? If you are still using 32 bit apps, will it actually map > as much as 2 gig of physical memory to the 32 bit apps so that (for example) > 3 high powered memory hungry 32 bit apps actually had 2 gig available to > each of them all the time? > > If anyone has run across any authoritive (on-line) reading on the subject I > would love to look at it. > > John W. Colby > Colby Consulting > www.ColbyConsulting.com > > _______________________________________________ > dba-Tech mailing list > dba-Tech at databaseadvisors.com > http://databaseadvisors.com/mailman/listinfo/dba-tech > Website: http://www.databaseadvisors.com > -- Gary Kjos garykjos at gmail.com