From owner-freebsd-hackers Mon Oct 28 23:52:49 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id XAA03804 for hackers-outgoing; Mon, 28 Oct 1996 23:52:49 -0800 (PST) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id XAA03799 for ; Mon, 28 Oct 1996 23:52:46 -0800 (PST) Received: from sax.sax.de (sax.sax.de [193.175.26.33]) by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id IAA24411; Tue, 29 Oct 1996 08:51:08 +0100 Received: (from uucp@localhost) by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id IAA01170; Tue, 29 Oct 1996 08:51:08 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.8.2/8.6.9) id IAA04345; Tue, 29 Oct 1996 08:36:20 +0100 (MET) From: J Wunsch Message-Id: <199610290736.IAA04345@uriah.heep.sax.de> Subject: Re: your mail To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Tue, 29 Oct 1996 08:36:20 +0100 (MET) Cc: cskim@cslsun10.sogang.ac.kr (Kim Chang Seob) Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <9610290231.AA27814@cslsun10.sogang.ac.kr> from Kim Chang Seob at "Oct 29, 96 11:31:48 am" X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E X-Mailer: ELM [version 2.4ME+ PL17 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk As Kim Chang Seob wrote: (Btw., Subject: and To: lines are great. Don't drop them!) > 1. after exec(), when process request his physical memory, > how many memory is allocated or what percent(%) is allocated? Nothing, i believe. All it gets is virtual memory. If some parts of the inherited text segment are in-core (which is very likely :), the new process will also have physical memory mapped. But there's no formula. > and where is frame allocation function? Which frame? What allocation? > 2. when process request his memory, > how memory is allocated? Page-faulted, as the new process needs it. I.e., as soon as memory is referenced but not yet in-core, it is brought in from secondary storage (file image, swap space). > 3. in vm_fault.c , VM_FAULT_READ_AHEAD is 4 and > VM_FAULT_READ_BEHIND is 3. > I don't know how 3 or 4 is selected? Empirical, i believe, but that's a question for the VM gurus. Btw., i suggest you a good book explaining a virtual memory architecture. The only one i know personally is ``The 4.4BSD Operating System. Design and Implementation.'' It's published by Addison-Wesley. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)