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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.mira.net.au!news.mel.connect.com.au!munnari.OZ.AU!news.hawaii.edu!ames!usenet.kornet.nm.kr!usenet.etri.re.kr!news.kreonet.re.kr!bofh.dot!usenet.seri.re.kr!bofh.dot!news.cais.net!bofh.dot!news.mathworks.com!fu-berlin.de!news.dfn.de!news.ruhr-uni-bochum.de!news.uni-stuttgart.de!uni-regensburg.de!newsserv.uni-bayreuth.de!news.tu-chemnitz.de!irz401!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Linux vs. FreeBSD ... (FreeBSD extremely mem/swap hungry) Date: 24 May 1996 21:46:05 GMT Organization: Private BSD site, Dresden Lines: 46 Message-ID: <4o5amt$n9l@uriah.heep.sax.de> References: <3188C1E2.45AE@onramp.net> <4mnsc5$6qo@sundial.sundial.net> <4mr1pk$cdi@dyson.iquest.net> <4n0dhd$cff@agate.berkeley.edu> <3194622D.41C67EA6@ami-chan.res.cmu.edu> <31A52667.794BDF32@zeus.co.uk> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: knews 0.9.6 X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E Damian Reeves <damian@zeus.co.uk> wrote: > On replacing with BSD, and copying over the .xsession files etc., by the > time the Xserver and xterms have started, 50MB of swap is in use!!! > I had to increase the swap space upto 250Mb just so we could actually > compile our server code. Funny, my swap partition is really fat with its 120 or so meg... and i've never seen it to overflow. Indeed, FreeBSD does a large amount of preemptive swapping, just in order to have free memory in case it will be needed. (The pages are still around in the physical memory, so if you need them back later, they can be reclaimed, and won't be read from swap -- but the swap is allocated already nevertheless.) This improves the response time in some circumstances. > At the moment, the machine is sitting there > with 1 user logged in, emacs, netscape and a couple of shells. top > reports that 59% of the swap space is in use! top also reports that > only 860k is available for buffer cache, ... FreeBSD minimizes the amount of ``free memory''. This is nothing that should alarm you. The used memory will keep buffer cache (from previously accessed files) and other old data that can easily be reclaimed when needed. OTOH, due to the preemptive swapping, the pages can easily be freed up for other purpose once they are needed. Actually, a large amount of free memory (except right after system boot) might be considered wasteful as well. :-) > over 1200k. This is extremely different to under linux, where it used > to stay around 12Mb-15Mb under use. One _known_ problem with X11 applications under FreeBSD was that the old BSD malloc() was rather wasteful with its VM usage, and at some point back, XFree86 didn't link against gnumalloc. However, the malloc has been rewritten from scratch since to overcome this. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)