Date: Tue, 23 Apr 2002 21:40:11 -0700 From: David Schultz <dschultz@uclink.Berkeley.EDU> To: Vallo Kallaste <kalts@estpak.ee> Cc: "Marc G. Fournier" <scrappy@hub.org>, Terry Lambert <tlambert2@mindspring.com>, freebsd-current@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: FreeBSD 4.5-STABLE not easily scalable to large servers ... ? Message-ID: <20020423214011.B3593@HAL9000.wox.org> In-Reply-To: <20020423184534.GA30212@myhakas.estpak.ee>; from kalts@estpak.ee on Tue, Apr 23, 2002 at 09:45:34PM %2B0300 References: <3CC4C683.F9AEF14E@mindspring.com> <20020423092909.N1721-100000@mail1.hub.org> <20020423184534.GA30212@myhakas.estpak.ee>
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Thus spake Vallo Kallaste <kalts@estpak.ee>: > Userspace processes will allocate memory > from UVA space and can grow over 1GB of size if needed by swapping. > You can certainly have more than one over-1GB process going on at > the same time, but swapping will constrain your performance. It isn't a performance constraint. 32-bit architectures have 32-bit pointers, so in the absence of segmentation tricks, a virtual address space can only contain 2^32 = 4G locations. If the kernel gets 3 GB of that, the maximum amount of memory that any individual user process can use is 1 GB. If you had, say, 4 GB of physical memory, a single user process could not use it all. Swap increases the total amount of memory that *all* processes can allocate by pushing some of the pages out of RAM and onto the disk, but it doesn't increase the total amount of memory that a single process can address. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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