| 1.t (1639) | 1.t (18715) |
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| 1.\" Copyright (c) 1986 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. --- 16 unchanged lines hidden (view full) --- 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)1.t 5.1 (Berkeley) 4/16/91 | 1.\" Copyright (c) 1986 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. --- 16 unchanged lines hidden (view full) --- 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)1.t 5.1 (Berkeley) 4/16/91 |
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| 33.\" 34.NH 35Motivations for a New Virtual Memory System 36.PP 37The virtual memory system distributed with Berkeley UNIX has served 38its design goals admirably well over the ten years of its existence. 39However the relentless advance of technology has begun to render it 40obsolete. --- 110 unchanged lines hidden (view full) --- 151to the amount of swap space as is done in the current design. 152Consequently, the new design will allow the maximum virtual memory 153to be the sum of physical memory plus swap space. 154For machines with no swap space, the maximum virtual memory will 155be governed by the amount of physical memory. 156.PP 157Another effect of the current technology is that the latency and overhead 158associated with accessing the file system is considerably higher | 34.\" 35.NH 36Motivations for a New Virtual Memory System 37.PP 38The virtual memory system distributed with Berkeley UNIX has served 39its design goals admirably well over the ten years of its existence. 40However the relentless advance of technology has begun to render it 41obsolete. --- 110 unchanged lines hidden (view full) --- 152to the amount of swap space as is done in the current design. 153Consequently, the new design will allow the maximum virtual memory 154to be the sum of physical memory plus swap space. 155For machines with no swap space, the maximum virtual memory will 156be governed by the amount of physical memory. 157.PP 158Another effect of the current technology is that the latency and overhead 159associated with accessing the file system is considerably higher |
| 159since the access must be be over the network | 160since the access must be over the network |
| 160rather than to a locally-attached disk. 161One use of the surplus memory would be to 162maintain a cache of recently used files; 163repeated uses of these files would require at most a verification from 164the file server that the data was up to date. 165Under the current design, file caching is done by the buffer pool, 166while the free memory is maintained in a separate pool. 167The new design should have only a single memory pool so that any --- 210 unchanged lines hidden --- | 161rather than to a locally-attached disk. 162One use of the surplus memory would be to 163maintain a cache of recently used files; 164repeated uses of these files would require at most a verification from 165the file server that the data was up to date. 166Under the current design, file caching is done by the buffer pool, 167while the free memory is maintained in a separate pool. 168The new design should have only a single memory pool so that any --- 210 unchanged lines hidden --- |