Date: Tue, 29 Oct 1996 08:36:20 +0100 (MET) From: J Wunsch <j@uriah.heep.sax.de> To: freebsd-hackers@freebsd.org (FreeBSD hackers) Cc: cskim@cslsun10.sogang.ac.kr (Kim Chang Seob) Subject: Re: your mail Message-ID: <199610290736.IAA04345@uriah.heep.sax.de> In-Reply-To: <9610290231.AA27814@cslsun10.sogang.ac.kr> from Kim Chang Seob at "Oct 29, 96 11:31:48 am"
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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. ;-)
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