Date: Thu, 03 Jun 1999 10:57:18 +0200 From: Thierry Herbelot <Thierry.Herbelot@alcatel.fr> To: Riccardo Veraldi <riccardo@righi.ml.org> Cc: Kent Stewart <kstewart@3-cities.com>, freebsd-questions@FreeBSD.ORG Subject: Re: 32-bit filesystem Message-ID: <3756436E.1D4088B3@telspace.alcatel.fr> References: <Pine.BSF.4.10.9906030958540.12815-100000@righi.ml.org>
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This is a multi-part message in MIME format. --------------6FA41D33C9D1A5438AEBF1EB Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hello, it seems there is some confusion, here : - under FreeBSD, all disk accesses are 32 bits (the OS : the kernel and the utilities are all 32 bits - even 64 bits on an alpha). - Kent's suggestion is about DMA access - versus PIO access (which is slower) ; I don't know of any problem related with using DMA on older disks (but there may be ?) I would suggest you install FreeBSD with the default (non-DMA) configuration, and then enable DMA on one controller (wdc0 or wdc1) - try and experiment. TfH Riccardo Veraldi wrote: > > thanks for the hints u gave me. > but I Wanted to ask if this thing of enabling 32 bit disk access > could make the system unstable or something. > Why if such speed improovement are obtained it is not included for default > in the kernel configuration ?? > For example I have very new disk drives on my FreeBSD box but also an old > one perhaps the old one does not support such a 32 bit access. > Do u think I can choose what drive to work with 32 bits and which one > to work as default ? > Could the system hang or something ? > thanks > > Rick > > On Mon, 31 May 1999, Kent Stewart wrote: > > > > > > > Riccardo Veraldi wrote: > > > > > > Hello, > > > I would like to know if FreeBSD has 32-bit disk access for default or if > > > I need to enable some other option in the configuration kernel file before > > > compiling it with 32 bit support for disk access. > > > > It isn't turned on by default; however, you can turn it on by doing a > > configuration at boot (boot -c). I add "flags 0xa0ffa0ff" to my wdc0 > > and wdc1 lines in my kernel configuration file. Examples are in the > > LINT file for wdc2. Changing it at boot lets you see the effect > > without regenerating the kernel. > > > > The transfer rate from my 13GB Maxtor UDMA 33 drive as determined by > > an "iozone 180" went from 3.8xMB/s to 11+MB/s on writes and 14+MB/s on > > reads. That is a significant difference. > > > > Kent > > > > > > > > thanks > > > > > > Rick > > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > > > with "unsubscribe freebsd-questions" in the body of the message > > > > -- > > Kent Stewart > > Richland, WA > > > > mailto:kstewart@3-cities.com > > http://www.3-cities.com/~kstewart/index.html > > > > SETI (Search for Extraterrestrial Intelligence) @ Home > > http://setiathome.ssl.berkeley.edu/ > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message --------------6FA41D33C9D1A5438AEBF1EB Content-Type: text/x-vcard; charset=us-ascii; name="thierry.herbelot.vcf" Content-Transfer-Encoding: 7bit Content-Description: Card for Thierry Herbelot Content-Disposition: attachment; filename="thierry.herbelot.vcf" begin:vcard n:Herbelot;Thierry tel;work:(+33) 1 46 52 47 23 x-mozilla-html:FALSE url:http://perso.cybercable.fr/herbelot org:CIT Nanterre adr:;;;;;; version:2.1 email;internet:thierry.herbelot@alcatel.fr x-mozilla-cpt:;-22032 fn:Thierry Herbelot end:vcard --------------6FA41D33C9D1A5438AEBF1EB-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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