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Re: Re: Re: Re: STOP Trading Memory for Speed

by perrin (Chancellor)
on Sep 25, 2002 at 23:26 UTC ( #200766=note: print w/replies, xml ) Need Help??

in reply to Re: Re: Re: STOP Trading Memory for Speed
in thread STOP Trading Memory for Speed

I read the problem. You can only address 4GB of physical memory, but you can use more in swap if you run Linux with PAE (Page Address Extensions), as available in Red Hat's "Advanced Server" distribution. There may be something similar for other OSes.

Note that I have not used this and can't speak about it from experience. My situation was with a process going over 2GB on a FreeBSD machine with 2GB of physical RAM.

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Re: Re: Re: Re: Re: STOP Trading Memory for Speed
by Anonymous Monk on Sep 25, 2002 at 23:56 UTC
    PAE lets the OS and specifically aware processes address more memory than what a simple pointer can address. If you turn it on then your OS can use more memory. That doesn't let any individual application push the 32-bit limit unless the OS supplies hooks for mapping and unmapping memory into what the program can directly address, and the program is aware of and uses those hooks.

    If you had a single process address over 4 GB of RAM on a 32-bit CPU, then the OS has to provide those hooks and the application has to be using it. It would make sense for BerkeleyDB to try this, but I don't know if does. If it doesn't and you want it to, you could pay Sleepycat to develop it for you.

      Good info. Thanks for stopping by, Anon.

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