From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <200401191940.i0JJeYVW024171@ccure.user-mode-linux.org> Subject: Re: [uml-user] Re: [uml-devel] Dynamic remount with variable COW stacking/merging needed, support for snapshot repilication In-Reply-To: Your message of "Mon, 19 Jan 2004 12:26:17 CST." References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii From: Jeff Dike Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Mon, 19 Jan 2004 14:40:34 -0500 To: Adam Heath Cc: James W McMechan , sdw@lig.net, user-mode-linux-user@lists.sourceforge.net, user-mode-linux-devel@lists.sourceforge.net adam@doogie.org said: > The problem is that you can't request multiple pages at once with > mmap. Only one page at a time(because the page you requested will > fault, which will pause the process while the system pages it in). No, mmap itself doesn't fault. It fiddles some data structures and returns immediately. The fault happens when the page is first touched. That's why the ubd IO thread touches the page after a request is satified my mmap - to fault the page in in an asynchronous way. I would love for there to be aio page fault notification. > In fact, mmap can be slower in some cases than normal reading, if the > kernel only pages in one block at a time(because of other reasons). In a lot of cases, actually. The tlb operations associated with changing mappings are expensive, and can outweigh a lot of copying. Jeff ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel