virtual memory 4502

re:

part of the instruction storage ref-change trace and paging simulation was also the program reoganization work that was mentioned previously

D. Hatfield & J. Gerald, Program Restructuring for Virtual Memory, IBM Systems Journal, v10n3, 1971

which was eventually released in 1976 as vs-repack

not only were various different sized pages simulated ... but the traces were also used for program re-organization to compact storage that was used together in minimum number of pages.

the "small" page advantage in severe real storage constrained configurations was to avoid unnecessarily bringing in parts of virtual storage ... that weren't going to be needed ... which might be brought in when using larger page sizes, increasing the total amount of real memory (unnecessarily).

however with program re-organization ... there would be high probability that adjacent storage would in-fact, be required ... so larger pages would tend to still occupy about the same amount of total real storage (compared to the smaller page sizes) ... with the advantage that the number of faults and fetches to bring in the virtual memory was reduced (fetching chunks in fewer, larger sizes)

as real storage sizes increased ... the benefit of high compaction and utilization from smaller pages would be less of an advantage ... and the larger number of page faults and transfers would become an increasingly significant throughput factor (vis-a-vis larger page sizes with fewer faults and fetches). also, the program restructuring tended to compact things w-o requiring the additional benefit of smaller page sizes.

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