Date: Fri, 23 Apr 2004 12:20:34 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Tim Kientzle <kientzle@FreeBSD.org> Cc: cvs-all@FreeBSD.org Subject: bad news for bsdtar.. Message-ID: <Pine.BSF.4.21.0404231145150.6894-100000@InterJet.elischer.org> In-Reply-To: <200404231627.i3NGRcVA096244@repoman.freebsd.org>
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done on a small subdirectory of our data... (only accounts starting with 849xxx) total data as reported by 'du': 9394486 KB (9GB) (note du takes links into account and doesn't count the same data twice) number of files with > 1 link: # find 849* -type f -links +1 | wc -l 240395 # total number of file directory entries.. # find 849* -type f | wc -l 598018 # total number of directories: %find 849* -type d | wc -l 51245 average filesize 23k but major file types are: jpeg images.. 100kb jpeg thumbnails, 3kb transaction descriptors 1kb ######################################################## the bad news: old (FreeBSD 2.x) tar with symlink hack %time ~/tar cf /dev/null 849* 5.309u 73.584s 21:15.44 6.1% 329+5150k 786697+0io 0pf+0w freebsd 4.8 tar %time tar cf /dev/null 849 5.159u 17.724s 4:08.97 9.1% 364+5863k 66144+0io 1pf+0w bsdtar %time ~/bsdtar cf /dev/null 849* 16.423u 68.141s 31:40.82 4.4% 402+1639k 784651+0io 0pf+0w It looks to me that the tar in 4.8 is doing something very sneeky with it's IOs.. maybe using mmap? maybe detecting /dev/null and instead discarding the data? maybe reading the entire file in a single read?
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