Date: Tue, 8 Nov 2005 10:24:01 +0100 From: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@FreeBSD.ORG> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: Ion-Mihai Tetcu <itetcu@people.tecnik93.com>, freebsd-ports@FreeBSD.ORG, le@FreeBSD.ORG Subject: Re: vinum, 5.x performance, ... (was: Re: ANNOUNCE: GNOME 2.12.1 has been merged into the ports tree) Message-ID: <A431DFC9-30C1-4C57-98A6-A0BC2CAECC3C@FreeBSD.ORG> In-Reply-To: <20051108101608.2nucv3s9us4k844k@netchild.homeip.net> References: <20051106.131413.122956532.yasu@utahime.org> <1131176568.3960.20.camel@shumai.marcuscom.com> <20051106.131413.122956532.yasu@utahime.org> <op.szszvnn89aq2h7@mezz.mezzweb.com> <ZhqaDxv9wJ@dmeyer.dinoex.sub.org> <20051107111800.e199ndcxa8s0c444@netchild.homeip.net> <20051107122458.27a1f9e7@it.buh.tecnik93.com> <20051107145645.rav7hhtlsggk4sss@netchild.homeip.net> <20051107214458.30ca47f2@it.buh.tecnik93.com> <20051108101608.2nucv3s9us4k844k@netchild.homeip.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On 08/11/2005, at 10:16, Alexander Leidinger wrote: > Ion-Mihai Tetcu <itetcu@people.tecnik93.com> wrote: > >> On Mon, 07 Nov 2005 14:56:45 +0100 >> Alexander Leidinger <Alexander@Leidinger.net> wrote: >> >>> Ion-Mihai Tetcu <itetcu@people.tecnik93.com> wrote: >>> >>> > On Mon, 07 Nov 2005 11:18:00 +0100 >>> > Alexander Leidinger <Alexander@Leidinger.net> wrote: >>> > >>> >> > - and performaces is a nightmare on atapi harddisks >>> >> >>> >> AFAIR 4.x enables the write cache (bad if there's a power failure >>> >> in the soft-updates case, since without native command =20 >>> queueing the >>> >> drivers may reorder writes witout the possibility to notify >>> >> soft-updates about it), > > I' a little bit confused now. The man page says the WC is enabled =20 > by default, > but I was under the impression, that it is disabled by default (I =20 > remember > there was a discussion about this long ago). On my systems it is =20 > disabled, > since I haven't removed the loader.conf line since the 4.x days. =20 > S=F8ren, is > this a bug in the man page or did I got it wrong? WC is enabled by default on modern FreeBSD's, it was tried to disable =20= it once but the performance hit quickly changed that decision. >>> > So on NCQ disks write_caching should be safe from consistency >>> > point-of-view ? >>> >>> AFAIK: Enabling the write cache doesn't mean you use NCQ. So just >>> because your drive is able to do NCQ, you shouldn't enable the write >>> cache. If your controller, your disk and the OS is able to use NCQ, >>> and you enable the use of NCQ, then everything is fine... assuming >>> the drive doesn't lie to you. AFAIR there are or there where some >>> drives which lie(d), but I don't remember the details. >> >> And finding out the what disk and controller use NCQ _and_ are >> supported by our drivers can be done how ? > > Asking sos@FreeBSD.org (CCed) would be a way to find it out... NCQ is not supported on FreeBSD at this time, support is in the works =20= and will get into -current once its far enough along. Note that TCQ =20 is only supported (and buggy since the PAE code was added) in 4.x. > At first I thought atacontrol tells you about it. But the =20 > "atacontrol cap > ad0" command just tells you about the capabilities of the drive, =20 > not which > of those capabilities are used by the driver (would be nice to have, > specially in the light of seeing TCQ enabled but knowing that you =20 > said is > doesn't work... at least with the previous implementation of ata). > > S=F8ren, is there a way to en-/disable some of the capabilities with =20= > atacontrol > or something else? Not as is, but it could be added along the way. However some of the =20 capabilties depends on both disk and controller and in most cases =20 also the OS have support for it. Furthermore some if the capabilities =20= only makes sense to change during boot. S=F8ren Schmidt sos@FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?A431DFC9-30C1-4C57-98A6-A0BC2CAECC3C>