Date: Mon, 27 Dec 1999 16:26:59 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Proposed patch to fix VN device (again) Message-ID: <199912280026.QAA34572@apollo.backplane.com> References: <7427.946340596@critter.freebsd.dk>
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: :In message <199912280012.QAA34430@apollo.backplane.com>, Matthew Dillon writes: : :> Sigh. Ok, I've fixed the VN device. Again. It looks like the removal of :> /dev/drum removed a little too much. We need the device infrastructure :> to support the VN device's use of swap backing store. :> :> This patch below is a commit candidate. It could use a review, then I'll :> commit it. : :Could you please explain why you need this ? : :-- :Poul-Henning Kamp FreeBSD coreteam member :phk@FreeBSD.ORG "Real hackers run -current on their laptop." :FreeBSD -- It will take a long time before progress goes too far! VN calls vm_pager_strategy() which collects I/O in filesystem buffers (bp)'s in order to cluster the I/O, and you cannot initiate I/O on filesystem buffers without a valid b_dev. So, the jist of the problem is that in order to get reasonable performance out of the thing (i.e. not issue 4K I/O's to the disk), we have to use filesystem buffers which means the bp must be properly initialized. -Matt Matthew Dillon <dillon@backplane.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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