Processor Usage Tracking via Statistical Sampling
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Solution Overview
Problem
Processor reliability counters face significant drift due to frequent power downs, leading to loss of usage data and the need for excessive write cycles in non-volatile memory, which can result in millions of one-time programmable fuses being required to maintain accurate usage records.
Innovation Solution
Implementing a statistical technique that reduces the number of writes to non-volatile memory by using random probability logic to determine when to record usage increments, allowing for fewer OTP fuses and minimizing drift through probabilistic determination of write events, thereby reducing the total number of writes and maintaining accurate usage tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If usage data is recorded at every power down cycle, then measurement precision is improved, but device complexity increases due to excessive OTP fuses required
Solution Approach 1:
The patent implements periodic sampling of usage data at predetermined intervals rather than continuous recording at every power down cycle. The counter accumulates usage data and only triggers a write to OTP memory when a threshold is reached, creating a periodic recording action that reduces the frequency of write operations and the number of OTP fuses required while maintaining acceptable measurement precision.
Solution Approach 2:
The patent changes the recording parameter from 'every power down cycle' to 'at predetermined intervals based on counter thresholds'. By modifying when and how frequently usage data is written to non-volatile memory, the system reduces the total number of write cycles and OTP fuses needed while still tracking processor usage accurately over time.
2Reliability
If counter value is saved at every power down, then reliability is improved, but loss of time increases due to frequent write cycles
Solution Approach 1:
The system performs write operations periodically based on counter thresholds rather than at every power down event. This reduces the frequency of time-consuming write cycles to non-volatile memory while ensuring that usage data is preserved at regular intervals, maintaining reliability without the time penalty of continuous recording.
Solution Approach 2:
The counter continuously accumulates usage data in volatile memory during processor operation, preparing the data for future write operations. This preliminary accumulation allows the system to perform fewer, more efficient write cycles to permanent storage while ensuring no usage data is lost, as the counter is continuously updating in the background.
3Measurement precision
If snapshot rate is increased to reduce drift, then measurement precision is improved, but loss of substance increases due to more OTP fuses consumed
Solution Approach 1:
The patent implements periodic recording at predetermined counter intervals rather than continuous high-rate sampling. The counter accumulates usage data and triggers write operations only when reaching predetermined thresholds, creating a periodic action that reduces OTP fuse consumption while maintaining measurement precision through regular sampling at strategically chosen intervals.
Solution Approach 2:
The system uses partial action by recording only when necessary (at counter thresholds) rather than continuously. This selective recording approach captures sufficient usage data to maintain measurement precision while consuming fewer OTP fuses, as writes are performed only when the counter reaches predetermined levels rather than at every possible moment.
Data Source
AI summary
In an embodiment, a processor includes measurement logic to measure a usage associated with the processor. The processor also includes statistical logic to determine, based on a statistical procedure, whether to provide a permission to record an increase in usage responsive to an indication that the usage has increased by a defined amount. The processor also includes control logic to record the defined increase in usage in non-volatile memory responsive to receipt of the permission to record from the statistical logic. Other embodiments are described and claimed.