nevin1@ihlpf.ATT.COM (00704a-Liber) (07/08/88)
[followups to comp.os.misc] In article <291@ns.nsc.com> ddb@ns.nsc.com (David Dyer-Bennet) writes: |In article <3950006@hplvly.HP.COM>, boyne@hplvly.HP.COM (Art Boyne) writes: |> ...on virtual memory machines, |> ...Having |> unmodifiable code segments therefore reduces disk activity. | No, it's whether the code segments *ACTUALLY ARE* modified that should |control disk activity; any decent virtual memory system must be able to |determine if a writable page has actually been written! So, truly pure |code does reduce paging, but the ABILITY to have impure code shouldn't |cost anything unless it's used. It still does, however. If an executing code segment is restricted to being unmodifiable, then it NEVER has to be written out to disk. If an executing code segment is modifiable, then a slightly more complex paging scheme needs to be used. It can be done, but not without cost. -- _ __ NEVIN J. LIBER ..!ihnp4!ihlpf!nevin1 (312) 510-6194 ' ) ) You are in a little twisting maze of / / _ , __o ____ email paths, all different. / (_</_\/ <__/ / <_ These are solely MY opinions, not AT&T's, blah blah blah