Date: Mon, 12 Mar 2007 11:48:58 -0700 From: Chuck Swiger <cswiger@mac.com> To: Dima Sorkin <dima.sorkin@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: limitiation on memory allocation Message-ID: <E47B8943-BB90-4E12-9CFD-278952B6B73F@mac.com> In-Reply-To: <e40293600703121120w7a013919l36103a19a930440a@mail.gmail.com> References: <e40293600703090632v3f25742g16e75708ded632ee@mail.gmail.com> <6.0.0.22.2.20070309094909.024c9dd0@mail.computinginnovations.com> <e40293600703090906n6f648580p5d46f45455ee707b@mail.gmail.com> <6.0.0.22.2.20070309133935.024b8fd0@mail.computinginnovations.com> <e40293600703121120w7a013919l36103a19a930440a@mail.gmail.com>
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On Mar 12, 2007, at 11:20 AM, Dima Sorkin wrote: > 2) 'maxdsiz' - Yes, as long as I keep 'maxdsiz + maxssiz' below > physical > memory size - everything is fine. Single process allocates > successfully > up to 'maxdsiz'. > When tried to put 'maxdsiz' > phys mem size, > indeed the system failed to boot, in all modes: > multiuser, singleuser, safe. > > So I derive from here that there is no way to cause a _single process_ > on FreeBSD to allocate more than physical memory size (?) It is certainly possible to configure FreeBSD to allow a single process to access more memory than is phyiscally installed. For example, I have a machine with 512MB of RAM, and set: kern.dfldsiz="1G" ...in /boot/loader.conf, and this works just fine. Admittedly, when a process does exceed 512MB in dsize, the system starts swapping quite a bit, but that's how virtual memory works. However, you cannot set maxdsiz greater than 4GB [1] if you are running a 32-bit version of FreeBSD. Enabling PAE will let the kernel access more than 4GB of physical RAM, but nothing is going to let a 32-bit system give more than 4 GB [1] to a single process...if you want to do that, then you'll need to switch to running a 64-bit version of FreeBSD. -- -Chuck [1]: Well, 3.5GB or 3GB, actually...due to the top portion of address space being occupied by PCI device space and the kernel.
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