From owner-freebsd-fs Tue Sep 12 18:27:32 2000 Delivered-To: freebsd-fs@freebsd.org Received: from mail-relay.eunet.no (mail-relay.eunet.no [193.71.71.242]) by hub.freebsd.org (Postfix) with ESMTP id C781D37B424 for ; Tue, 12 Sep 2000 18:27:29 -0700 (PDT) Received: from login-1.eunet.no (login-1.eunet.no [193.75.110.2]) by mail-relay.eunet.no (8.9.3/8.9.3/GN) with ESMTP id DAA56361; Wed, 13 Sep 2000 03:27:25 +0200 (CEST) (envelope-from mbendiks@eunet.no) Received: from localhost (mbendiks@localhost) by login-1.eunet.no (8.9.3/8.8.8) with ESMTP id DAA85567; Wed, 13 Sep 2000 03:27:25 +0200 (CEST) (envelope-from mbendiks@eunet.no) X-Authentication-Warning: login-1.eunet.no: mbendiks owned process doing -bs Date: Wed, 13 Sep 2000 03:27:25 +0200 (CEST) From: Marius Bendiksen To: Christopher Stein Cc: freebsd-fs@FreeBSD.ORG Subject: Re: how mmap buffer writes handled? In-Reply-To: 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 > How are these data structures and statistics kept meaningful > under mmapped workloads? Most architectures that have an MMU, such as the x86, have a bit in their page tables or equivalent that will indicate whether a page has been modified since the last time that bit was cleared. This can be sampled and cleared in one go. On architectures lacking an MMU, I think the logical approach would be to use some of the protection facilities or such to force an exception to be raised when accessing the page for write, and updating the statistics based on that. Marius To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message