Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!ames!amdahl!terry From: terry@uts.amdahl.com (Lewis T. Flynn) Newsgroups: comp.lang.asm370 Subject: Re: New System/3x0 Instruction Message-ID: Date: 15 Mar 91 20:11:53 GMT References: <9103101551.AA15585@ucbvax.Berkeley.EDU> Reply-To: terry@amdahl.uts.amdahl.com (Lewis T. Flynn) Distribution: inet Organization: Amdahl Corporation, Sunnyvale CA Lines: 27 In article <9103101551.AA15585@ucbvax.Berkeley.EDU> IBM 370 Assembly Programming Discussion List writes: >I am in the process of proposing a new 370 (etc.) machine code, >to be submitted as a SHARE requirement, probably in the >Numerically Intensive Computing (NIC) project. >=========================================================================== >Statement: Create a new OP code, Move and Discard Character Long. >Enhance the Operating System paging services to recognize >moves of entire pages, and perform these by updating tables. [further discussion elided] You may want this to be a SHARE requirement, but not for a new machine instruction. All the necessary features are already there. Rather, this is a request for new operating system function in MVS or VM. Other 370 OSes already give at least some capability in this area or have major features coming. KeyKOS gives the programmer direct control of his address space, UTS currently has shared memory segments and will have the SVR4 mmap system call eventually, and I presume AIX/370 is similar. Both shared memory and mmap allow you to map data into specific addresses in your address space, to unmap it, and to map it in somewhere else. They have different characteristics and limitations and I suspect that mmap is much better for your needs. Regardless, none of this is exactly free (page table and tlb manipulation is pretty expensive no matter who does it) and you should carefully examine your algorithms to avoid the necessity, if possible. Terry