From owner-freebsd-hackers Tue Jun 23 02:21:42 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id CAA00805 for freebsd-hackers-outgoing; Tue, 23 Jun 1998 02:21:42 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from implode.root.com (implode.root.com [198.145.90.17]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id CAA00719 for ; Tue, 23 Jun 1998 02:21:13 -0700 (PDT) (envelope-from root@implode.root.com) Received: from implode.root.com (localhost [127.0.0.1]) by implode.root.com (8.8.5/8.8.5) with ESMTP id CAA20998; Tue, 23 Jun 1998 02:17:27 -0700 (PDT) Message-Id: <199806230917.CAA20998@implode.root.com> To: zhihuizhang cc: hackers Subject: Re: Questions concerning cache buffer In-reply-to: Your message of "Mon, 22 Jun 1998 14:45:46 EDT." From: David Greenman Reply-To: dg@root.com Date: Tue, 23 Jun 1998 02:17:27 -0700 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG >(1) What is a bogus page? How it is used? It is used as a placeholder for doing partial buffer reads when a modified page exists in the another part of the buffer. >(2) Does the paged I/O array b_pages[] of a buffer alway have *contiguous* >pages? No. >(3) A page can be partially valid and/or dirty. What is the relationship >between being valid and being dirty? Not sure I can answer this to your satisfaction, but support for partial valid/dirty pages is there mainly to support filesystems with less-than- pagesize blocks. -DG David Greenman Co-founder/Principal Architect, The FreeBSD Project To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message