From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3D8054D5.B385C83@scs.ch> Date: Thu, 12 Sep 2002 10:48:21 +0200 From: Martin Maletinsky MIME-Version: 1.0 Subject: kiobuf interface / PG_locked flag Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org, kernelnewbies@nl.linux.org List-ID: Hello, I just read about the kiobuf interface in the Linux Device Driver book from Rubini/Corbet, and there is one point, which I don't understand: - map_user_kiobuf() forces the pages within a user space address range into physical memory, and increments their usage count, which subsequently prevents the pages from being swapped out. - lock_kiovec() sets the PG_locked flag for the pages in the kiobufs of a kiovec. The PG_locked flag prevents the pages from being swapped out, which is however already ensured by map_user_kiobuf(). (1) What is the reason to call lock_kiovec()? (2) Are there any additional effects (other than prevent the page from being swapped out) resulting from a set PG_locked flag? (3) Does anyone know a more detailed documentation of the kiobuf interface, than the book mentioned above? P.S. please put me on CC in your reply, since I am not in the mailing list. Thanks for any help, best regards Martin Maletinsky -- Supercomputing System AG email: maletinsky@scs.ch Martin Maletinsky phone: +41 (0)1 445 16 05 Technoparkstrasse 1 fax: +41 (0)1 445 16 10 CH-8005 Zurich -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/