Virtual Address Generator for Mobile MMU TLB Miss Reduction
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Solution Overview
Problem
The performance of memory management units (MMUs) in mobile devices is degraded during image rotation due to large address differences between adjacent transactions, leading to translation lookaside buffer (TLB) misses, which act as a performance bottleneck.
Innovation Solution
A method and system that utilize two virtual address generators, one based on pixel coordinates and image data size, and another based on tile size and transaction details, to generate virtual addresses, minimizing address differences and reducing TLB misses by selecting the appropriate generator based on user intervention and processing mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single virtual address generator is used, then the device complexity is low, but the MMU performance degrades during image rotation due to large address differences causing TLB misses
Solution Approach 1:
The patent divides the address generation function into two separate virtual address generators: a first virtual address generator for non-rotated images and a second virtual address generator for rotated images. This segmentation allows each generator to be optimized for its specific use case, improving MMU performance during image rotation without requiring a completely complex unified system.
Solution Approach 2:
The patent implements dynamic selection between the first and second virtual address generators based on rotation mode information. The system dynamically switches between different address generation algorithms depending on whether image rotation is detected, allowing optimal performance adaptation without static complexity.
2Reliability
If the first virtual address generator is used for rotated images, then the device complexity remains low, but TLB misses increase due to large address differences between adjacent transactions
Solution Approach 1:
The patent applies local quality by making the second virtual address generator specifically optimized for rotated image scenarios. This generator uses tile-based address calculation that maintains smaller address differences for adjacent pixels in rotated images, improving TLB hit rate locally for the specific case of image rotation without affecting other operations.
Solution Approach 2:
The patent changes the address generation parameters and algorithm based on rotation mode. When rotation is detected, the system switches to a different address calculation formula that accounts for the rotated coordinate system, thereby maintaining address continuity and reducing TLB misses for rotated images.
3Productivity
If two virtual address generators are implemented, then TLB misses are reduced during image rotation, but the ease of operation increases due to the need to select between generators
Solution Approach 1:
The patent implements self-service by automatically detecting the rotation mode and selecting the appropriate virtual address generator without user intervention. The system monitors rotation mode information and autonomously switches between the first and second generators, maintaining ease of operation while improving performance.
Solution Approach 2:
The patent uses dynamic selection logic that automatically adapts between the two virtual address generators based on real-time rotation mode detection. This dynamic behavior eliminates the need for manual configuration or user decision-making, preserving ease of operation while optimizing system performance for the current operating conditions.
Data Source
AI summary
A method of generating a virtual address in a data processing system controller includes receiving and analyzing attribute information which indicates whether user intervention is possible for allocating a memory buffer for storing image data; enabling one of a first virtual address generator or a second virtual address generator based on an analysis result; and generating the virtual address of a data transaction using the enabled virtual address generator.