🚀 go-pugleaf

In article <9103101551.AA15585@ucbvax.Berkeley.EDU> IBM 370 Assembly
        Programming Discussion List <ASM370@OHSTVMA.BITNET> 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