Date: Fri, 27 Aug 1999 16:51:20 +0930 From: Greg Lehey <grog@lemis.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Matthew Dillon <dillon@apollo.backplane.com>, Christopher Masto <chris@netmonger.net>, "John W. DeBoskey" <jwd@unx.sas.com>, julian@whistle.com, freebsd-current@FreeBSD.ORG Subject: Re: -current kernel problems (spec_getpages & vm_fault) Message-ID: <19990827165120.Y483@freebie.lemis.com> In-Reply-To: <3839.935736904@critter.freebsd.dk>; from Poul-Henning Kamp on Fri, Aug 27, 1999 at 08:55:04AM %2B0200 References: <19990827160950.X483@freebie.lemis.com> <3839.935736904@critter.freebsd.dk>
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On Friday, 27 August 1999 at 8:55:04 +0200, Poul-Henning Kamp wrote: > In message <19990827160950.X483@freebie.lemis.com>, Greg Lehey writes: >> On Thursday, 26 August 1999 at 16:25:14 -0700, Matthew Dillon wrote: >>>>>> int devminor; /* minor number */ >>>>>> >>>>>> devminor = minor(dev); >>>>>> + dev->si_bsize_phys = DEV_BSIZE; >>>>>> + dev->si_bsize_best = BLKDEV_IOSIZE; >>>>>> + dev->si_bsize_max = MAXBSIZE; >>>>> >>>>> Bingo! Thank you. >>>> >>>> Cool, I expect grog will commit it soon. >> >> So did I until I read this message. >> >>> The patch for ccd is not quite right. Here is the patch from my >>> big fat patch at http://www.backplane.com/FreeBSD4/ >>> >>> The problem is that you cannot simply set the physical sector >>> size to DEV_BSIZE if the underlying device has a larger sector >>> size. If you do, specfs's blocksize alignment (another fix in >>> my big fat patch) will be incorrect and result in an I/O error >>> on the physical media. >>> >>> For example, swap-backed VN devices have a sector size of one page, >>> i.e. 4K. >> >> Vinum currently doesn't track the sector size of the drives. I'll >> have to put some code in there to DTRT. In the meantime, I'll set >> si_bsize_best to 4K in the hope that this will be OK. Are there any >> larger block sizes in current use? > > 4K is probably too conservative, it only applies if you have a > swap-backed vn device at the bottom, which would be a truly > weird thing to do with vinum. I think I've heard of people doing things like this. Cybernet were thinking of it a long time ago, but I think I've talked them out of it. > Don't spend too much time on tracking the sector size yet. I think > the si_bsize stuff needs some thinking before we do more with it. OK, I'll set it to 4 kB at the moment and make a note to myself to fix it when dev_t stops changing. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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