Date: Sun, 27 Feb 2005 06:15:23 -0800 From: "David G. Lawrence" <dg@dglawrence.com> To: "O. Hartmann" <ohartman@uni-mainz.de> Cc: freebsd-amd64@freebsd.org Subject: Re: Kernel/Userland Mem-Space Tuning (1/3 on IA32) Message-ID: <20050227141523.GG3258@opteron.dglawrence.com> In-Reply-To: <4221C943.8080500@uni-mainz.de> References: <4221C943.8080500@uni-mainz.de>
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> Hello. > I read about address space division of recent operating systems like > Linux and Windows XP. > In both cases, the whole address space of the 32 or 64 Bit system is > divided into halfes, 2GB for > kernel, 2 GB for process(es) (speaking in 32Bit words). The same in > 64bit systems like AMD64. > Those who happily utilize an AMD64 based machine are not (yet) involved > by this problem, > but on recent 32 Bit architectures someone can run out of process space, > like me! Some > geophysical modelling software needs more than the allowed 2GB address > space and therefore > I would like to ask whether FreeBSD (my preferred OS) has a 'knob' to > change the kernel/userland parity > of the address space like it is done in Windows with a special knob at > boot time (/W3GB I think, but I'm not > sure about the exakt syntax but I know someone can change the half by > half parity towards 1 to 3 in > XP). I'm not sure whether FreeBSD divides kernel/userland address space > this way, I know Linux and > Windows does and on Windows we changed this (not yet on Linux and not > yet on our FreeBSD machines > (OS version >5.0, mostly FreeBSD 5.3-R or 5.4-PRERELEASE). > > Any help is appreciated. FreeBSD divides the 32bit virtual address space with 1GB for the kernel and 3GB for user processes. This can be changed with some kernel compile- time constants (primarily KVA_PAGES, however NKPT may also need to be increased if the kernel address space is increased). -DG David G. Lawrence President Download Technologies, Inc. - http://www.downloadtech.com - (866) 399 8500 TeraSolutions, Inc. - http://www.terasolutions.com - (888) 346 7175 The FreeBSD Project - http://www.freebsd.org Pave the road of life with opportunities.
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