SIMT Instruction Scalarization for Reducing Redundant Execution
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Solution Overview
Problem
Existing single instruction multiple thread (SIMT) processing architectures face inefficiencies due to redundant execution of deterministic instructions across multiple threads, leading to increased power consumption and resource utilization, particularly for operations that are complex or executed by only a few threads.
Innovation Solution
Adapt the SIMT execution model to perform certain operations using a serial execution unit, where instructions intended for parallel execution are recast for execution by a serial execution unit through a process called scalarization, utilizing peeling loops to partition and unwind thread execution, and optimizing these loops with compiler analysis to determine uniformity and reduce unnecessary operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If deterministic instructions are executed in parallel across multiple threads in SIMT architecture, then throughput is improved, but power consumption and resource utilization increase
Solution Approach 1:
The patent applies partial action by executing deterministic instructions only once on a serial execution unit rather than redundantly on all parallel threads. The compiler identifies instructions with uniform operands across threads and executes them partially (once) instead of fully (on every thread), reducing power consumption while maintaining correctness for deterministic operations.
2Productivity
If deterministic instructions are executed in parallel across multiple threads in SIMT architecture, then throughput is improved, but device complexity increases
Solution Approach 1:
The patent segments the execution units into two distinct types: serial execution units for deterministic instructions with uniform operands, and parallel execution units for non-deterministic instructions. This segmentation allows each unit type to be optimized independently, reducing the complexity of individual execution units while maintaining overall system throughput.
Solution Approach 2:
The serial execution unit serves a universal purpose by handling all deterministic instructions that have uniform operands across threads, regardless of which specific thread would have executed them in a fully parallel model. This multi-functional approach consolidates work that would otherwise be distributed across multiple parallel units, reducing overall device complexity.
3Use of energy by moving object
If instructions are recast for serial execution through scalarization, then power efficiency is improved, but execution time for individual instructions increases
Solution Approach 1:
The scalarization process applies partial action by executing deterministic instructions once rather than redundantly on every thread. While the serial execution unit takes longer per instruction compared to parallel execution, the overall time is reduced because the instruction is executed only once instead of N times for N threads, and the serial unit can complete the single execution faster than coordinating N parallel executions.
Data Source
AI summary
Apparatuses, systems, and techniques to adapt instructions in a SIMT architecture for execution on serial execution units. In at least one embodiment, a set of one or more threads is selected from a group of active threads associated with an instruction and the instruction is executed for the set of one or more threads on a serial execution unit.