Date: Mon, 15 Sep 2003 07:07:26 +0200 (SAST) From: Irvine Short <irvine@sanbi.ac.za> To: Alex de Kruijff <freebsd@akruijff.dds.nl> Cc: freebsd-stable@freebsd.org Subject: Re: Large memory issues on 4-STABLE Message-ID: <20030915070012.U36360@fling.sanbi.ac.za> In-Reply-To: <20030914162113.GA89177@dds.nl> References: <20030913092804.S46465@fling.sanbi.ac.za> <20030913123257.C51554@fling.sanbi.ac.za> <20030914162113.GA89177@dds.nl>
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On Sun, 14 Sep 2003, Alex de Kruijff wrote: > On Sat, Sep 13, 2003 at 03:48:21AM -0700, David G. Lawrence wrote: > > > David Lawrence said: > > > > Sorry, due to design issues, it isn't possible to have virtual sizes > > > >larger than about 3GB on FreeBSD. This is because the kernel is mapped in > > > > > > OK, fair enough. Is this going to be any different in FreeBSD with PAE > > > (Intel's scheme for 32bit stuff using > 4GB RAM)? > > > > No, this has nothing to do with the size of physical memory. It is a limit > > on the size of a process's virtual address space. > > > > > Should I try 5.1? Or isn't 4.9 going to have PAE support anyway? > > > > All versions of FreeBSD have this limitation. Yes, I understand that. What I am saying is, is that the general story out there is that with a 32 bit operatng system no process can address more than 4GB of RAM. Fine. David said that in FreeBSD I cannot in practicality address more than about 3GB of RAM. Also fine. However we have a situation where if I set MAXDSIZ to 2048 or above then things break, so FreeBSD right now has an effectivce limit of 2GB per process. Is this to be considered a bug or a feature? Then, with the PAE support, lets say I have 8GB of RAM. Will those same design limitations restrict me to 3GB of RAM, or 2GB, or will I be able to have a single process addressing 4GB all by itself? This is relevant to the work we're doing - some of my users actually really do need this amount of memory. Cheers, -- Irvine > > > > > Given what David says though, why do I have a problem with MySQL getting > > > thread errors with MAXDSIZ 2048 or greater? > > > > > > Why does tcsh's "limit" report datasize unlimited when MAXDSIZ is over > > > 2048? > > > > Probably a signed arithmetic problem. 2048MB is 2^31 bits, which is the > > largest number that can be represented in a 32 bit signed int. > > Sorry but 2^31 is the lowest number availible in a 32 bit signed int and > 2^31-1 is the largest number. The 32th bit indicates the number is > negitive. Irvine Short Sys Admin SANBI, University of the Western Cape, South Africa http://www.sanbi.ac.za tel: +27-21-959 3645 cel: +27-82-494 3828
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