Path: utzoo!news-server.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!usc!rpi!masscomp!peora!tarpit!bilver!dandrews
From: dandrews@bilver.uucp (Dave Andrews)
Newsgroups: comp.lang.asm370
Subject: Re: New System/3x0 Instruction
Keywords: NIC
Message-ID: <1991Mar13.171515.28275@bilver.uucp>
Date: 13 Mar 91 17:15:15 GMT
References: <1991Mar8.173043.26275@aplcen.apl.jhu.edu>
Organization: W. J. Vermillion - Winter Park, FL
Lines: 25

In article <1991Mar8.173043.26275@aplcen.apl.jhu.edu> dave@visual1.jhuapl.edu (Dave Weintraub) 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.
>
>  ... justification deleted ...

Dave, maybe what you want is not an instruction, but a supervisor service
that defines common pages in the same (or different) address space?

This mythical service could be used to say "Make the 4K pages at location
X and Y point to the same physical page.  Discard the existing data (if
any) at Y."  Any changes made to the address space at X would be immediately
echoed at location Y.  Another request might be to undo the association,
i.e. to invalidate one of the page table entries.

This might be a useful cross-memory communication medium, and also be
of value in moving LARGE data areas.  I'm not sure that the path length
is necessarily shorter than moving 16MB however    :-)

- David Andrews     tarpit!bilver!dandrews