Page Table Synchronization via RCsync Instruction
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Solution Overview
Problem
In multiprocessor computing environments, existing technologies face challenges in synchronizing updates of status indicators in page tables across processors, leading to inefficiencies in memory management operations such as bulk operations and process termination, as updates are not guaranteed to be committed in a timely manner.
Innovation Solution
A synchronization capability is introduced, where a processor initiates an RCsync instruction to ensure that pending updates in cached page table entries are committed to memory, allowing for the invalidation of selected cache entries and facilitating operations like bulk memory changes and process teardowns by ensuring all updates are reflected in memory before proceeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cached copies of page table entries are maintained in TLBs to optimize performance, then access speed is improved, but consistency between cache and memory is worsened
Solution Approach 1:
The patent applies preliminary action by initiating a synchronization operation (RCsync instruction) before performing bulk operations or process termination. This ensures that all pending updates to page table status indicators in cached copies are committed to memory in advance, guaranteeing consistency before the operation proceeds. The synchronization operation is performed proactively to prevent potential inconsistency issues.
2Productivity
If updates to page table entries are deferred in cached copies, then productivity is improved, but update commitment timeliness is worsened
Solution Approach 1:
The patent implements periodic action by using synchronization operations at specific intervals or trigger points in the system operation. The RCsync instruction is executed periodically or at critical moments (before bulk operations, process termination) to commit accumulated updates. This allows the system to maintain high productivity during normal operation while ensuring timely commitment of updates at appropriate intervals.
3Productivity
If bulk operations are performed without synchronizing updates first, then productivity is improved, but reliability is worsened
Solution Approach 1:
The patent applies preliminary action by requiring a synchronization operation to be initiated before bulk operations are executed. The RCsync instruction ensures that all pending updates to page table status indicators are committed to memory before the bulk operation proceeds. This preliminary synchronization step guarantees reliability while maintaining productivity, as the actual bulk operation can still be performed efficiently once synchronization is complete.
Data Source
AI summary
A synchronization capability to synchronize updates to page tables by forcing updates in cached entries to be made visible in memory (i.e., in in-memory page table entries). A synchronization instruction is used that ensures after the instruction has completed that updates to the cached entries that occurred prior to the synchronization instruction are made visible in memory. Synchronization may be used to facilitate memory management operations, such as bulk operations used to change a large section of memory to read-only, operations to manage a free list of memory pages, and/or operations associated with terminating processes.