Date: Mon, 24 Mar 2008 05:12:18 +0000 (UTC) From: Vadim Goncharov <vadim_nuclight@mail.ru> To: freebsd-current@freebsd.org Subject: Re: RELEASE discs & ISO images (for future) Message-ID: <slrnfuee1i.2s9k.vadim_nuclight@hostel.avtf.net> References: <slrnftsefa.1dfj.vadim_nuclight@hostel.avtf.net> <200803181359.m2IDxpdW017638@lurza.secnetix.de>
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Hi Oliver Fromme! On Tue, 18 Mar 2008 14:59:51 +0100 (CET); Oliver Fromme wrote about 'Re: RELEASE discs & ISO images (for future)': >>>>> 224655360 7.0-RELEASE-i386-livefs.iso >>>>> 94493696 7.0-RELEASE-i386-livefs.iso.uzip (16k cluster) >>>>> 110188032 7.0-RELEASE-i386-livefs.iso.uzip (2K cluster) >>>>> >>>>> So the difference is 124 MB for 16K cluster size, and >>>>> 109 MB for 2K cluster size (which is noticably faster >>>>> during access). Actually the space savings will be a >>>>> bit less, because the /boot directory (about 30 MB) >>>>> won't be compressed. So the real gain is probably a >>>>> little less than 100 MB in the 2K case. >>>> >>>> By the way, the maxmum cluster size is 127k or 130048 with uzip, >>>> if you want to maximize the compression ratio. >>> That would make the live FS painfully slow, and it wouldn't >>> make a big difference from the default (16K). >>> It is already noticeably slow with the default cluster size >>> of 16K on my test machine (a 1 GHz VIA C3), so would rather >>> prefer to use 2K cluster size, even though compression will >>> be not quite as good. (2K is the minimum, less than that >>> doesn't make sense for CD9660 media because the physical >>> sector size is 2K.) >> >> How much is slowdown from 2K to 16K ? > It's very noticeable. I haven't done benchmarks, but > you can clearly feel the difference. A find(1) takes > more time. Also man(1) takes longer until the page > comes up. Any kind of random access is slower, unless > all data is already cached. A find(1) on livefs is useless most of time. But man(1) is more valuable, though. > Interestingly there doesn't seem to be a difference > between 2K and 4K, and the difference to 8K is only > very small. But there is a noticeable difference > between 8K and 16K. I don't know why, maybe it's > related to FreeBSD's handling of FS buffers. So > maybe the "optimal" cluster size for an acceptable > performance/compression ratio would be 8K. Agreed. -- WBR, Vadim Goncharov. ICQ#166852181 mailto:vadim_nuclight@mail.ru [Moderator of RU.ANTI-ECOLOGY][FreeBSD][http://antigreen.org][LJ:/nuclight]
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