Number: 2236

Date: 24-Sep-84 12':52':21

Submitter: Masinter

Source: Masinter

Subject: want Huge (>28 bit) virtual address space for arrays

Assigned To: 

Attn: masinter, purcell, vanmelle, lisp

Status: Open

In/By: 

Problem Type: Design - Impl

Impact: Moderate

Difficulty: Hard

Frequency: 

Priority: Perhaps

System: Operating System

Subsystem: Virtual Memory

Machine: 

Disk: 

Lisp Version: 24-Sep-84 09':49':01

Source Files: 

Microcode Version: 5124

Memory Size: 4096

File Server: 

Server Software Version: 

Disposition: '
["Sannella.PA" "24-Sep-84 14':42':42" Priority':(->Perhaps) System':(->Operating% System) Subsystem':(->Virtual% Memory)]

Description: '
while the virtual address space on our machines for arbitrary data and reference is generally constrained by the map hardware, there is some possibility that we could implement a very large virtual address space specifically for arrays, with microcoded access to make the performance penalty relatively small.  '
'
If we made bitmaps be 2 dimensional 1-bit arrays, we could probably also put bitmaps out into extended space (once ''real virtual space'' was exhausted).'
'
This is actually not too cockeyed, and might let us advertise, e.g., a 48 bit virtual address space.'
'
Larry'
'
'


Workaround: 

Test Case: 

Edit-By: Sannella.PA

Edit-Date: 24-Sep-84 14':42':42