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Xref: sserve comp.unix.admin:14304 comp.unix.bsd:12769 comp.unix.internals:6354 comp.unix.wizards:31261 Newsgroups: comp.unix.admin,comp.unix.bsd,comp.unix.internals,comp.unix.wizards Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!elroy.jpl.nasa.gov!usc!howland.reston.ans.net!pipex!uknet!festival!castle.ed.ac.uk!richard From: richard@castle.ed.ac.uk (Richard Tobin) Subject: Re: why is altering MINFREE discouraged ? References: <1993Oct15.212623.14509@aw101.iasl.ca.boeing.com> <PCG.93Oct18191520@decb.aber.ac.uk> Message-ID: <CF5DG9.6F@festival.ed.ac.uk> Sender: news@festival.ed.ac.uk (remote news read deamon) Organization: University of Edinburgh Date: Tue, 19 Oct 1993 13:57:41 GMT Lines: 21 In article <PCG.93Oct18191520@decb.aber.ac.uk> pcg@aber.ac.uk (Piercarlo Grandi) writes: >Briefly: when looking for a cylinder group with free blocks to extend a >file, the FFS chooses a cylinder group *at random*, for some rather good >reasons. If the amount of free space is below a certain threshold, it >must try several cylinder groups to find one with free blocks, and this >is rather expensive. The threshold is around 10% for 8KB/1KB blocks and 5% >for 4KB/512B blocks, according to the paper. Just how expensive is it? Even large partitions typically have ~100 cylinder groups. Since the search doesn't involve reading the disk I wouldn't have thought this was much of a problem for modern (ie fast) cpus. Does anyone have any figures? It does seem a bit much to waste 200Mb on a 2Gb disk! - Richard -- "For thousands of years, [homoeopathic magic] was known to the sorcerors of ancient India, Babylon and Egypt, as well as of Greece and Rome, and at this day it is still resorted to by cunning and malignant savages in Australia, Africa and Scotland." - J G Frazer, The Golden Bough