From owner-freebsd-fs Fri Sep 8 8:17:47 2000 Delivered-To: freebsd-fs@freebsd.org Received: from wally.eecs.harvard.edu (wally.eecs.harvard.edu [140.247.60.30]) by hub.freebsd.org (Postfix) with ESMTP id 6C18A37B43F for ; Fri, 8 Sep 2000 08:17:41 -0700 (PDT) Received: from localhost (stein@localhost) by wally.eecs.harvard.edu (8.10.0/8.10.0) with ESMTP id e88FHdW19478 for ; Fri, 8 Sep 2000 11:17:40 -0400 (EDT) Date: Fri, 8 Sep 2000 11:17:39 -0400 (EDT) From: Christopher Stein X-Sender: stein@wally To: freebsd-fs@freebsd.org Subject: how mmap buffer writes handled? Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Hello, Suppose a file is mmapped and the application writes into a previously clean buffer. This will not pass through the syscall interface and the OS has no way of triggering bdirty() and moving the buffer onto the dirty queue. The only way the OS has of knowing if the buf is dirty is by examining the page table hardware bits. How are buffers dirtied by mmap moved onto the dirty queue? IS this done synchronously by some kind of software intercept of the page table operations or are the buffers moved from the clean to dirty queues in the background? thnx, -Chris To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message