Date: Fri, 7 Dec 2001 19:32:37 -0600 From: Mike Meyer <mwm@mired.org> To: "Roger 'Rocky' Vetterberg" <listsub@rambo.simx.org> Cc: questions@freebsd.org Subject: Re: mount_mfs with softupdate generates panic Message-ID: <15377.28085.155538.40480@guru.mired.org> In-Reply-To: <61500916@toto.iv>
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Roger 'Rocky' Vetterberg <listsub@rambo.simx.org> types: > Ceri wrote: > >On Fri, Dec 07, 2001 at 06:08:22PM +0100, Roger 'Rocky' Vetterberg wrote: > >>Has anyone used memory disks, with softupdates enabled, succesfully? > >There isn't any point. > > > What do you mean no point? > I agree, the performance gained of using Soft Updates on a memory disk > is probably small, but as I mentioned, this was done purely for > performance, hence the noatime and async flags. Async is ignored if you turn on soft updates. Soft updates isn't stupid - it realizes that if you've turned on soft udpates on the filesystem, async is not only irrelevant, but dangerous. > Im by no means a filesystem expert, but Soft Updates should improve > performance on memory disks as well as regular harddrives, right? Not necessarily. Soft updates orders writes from the buffer cache to the hard disk. If your memory disk is working properly, those writes never happen, because the disk and the buffer cache are one and the same thing. But yes, the system shouldn't panic you you mount your mfs disk async. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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