In the S/370 architecture, a storage key is a control field associated with each page- sized frame of real memory. Two bits of that key that are relevant for page replace- ment are the reference bit and the change bit. The reference bit is set to 1 when any address within the frame is accessed for read or write, and is set to 0 when a new page is loaded into the frame. The change bit is set to 1 when a write operation is per- formed on any location within the frame. Suggest an approach for determining which page frames are least-recently-used, making use of only the reference bit.

In the S/370 architecture, a storage key is a control field associated with each page- sized frame of real memory. Two bits of that key that are relevant for page replace- ment are the reference bit and the change bit. The reference bit is set to 1 when any address within the frame is accessed for read or write, and is set to 0 when a new page is loaded into the frame. The change bit is set to 1 when a write operation is per- formed on any location within the frame. Suggest an approach for determining which page frames are least-recently-used, making use of only the reference bit.

Systems Architecture

7th Edition

ISBN:9781305080195

Author:Stephen D. Burd

Publisher:Stephen D. Burd

Chapter11: Operating Systems

Section: Chapter Questions

Problem 21VE

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