Cache Management for Sequential Workloads

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Solution Overview

Problem

Existing storage systems face inefficiencies in managing cache and least recently used lists, particularly with sequential workloads, leading to increased CPU consumption, lock contention, and decreased performance due to the conventional practice of storing data objects in these lists, which are not optimized for sequential access patterns.

Innovation Solution

The technique involves identifying the type of workload and only adding data objects associated with non-sequential workloads to the least recently used list, while reclaiming storage space for sequential workloads, thereby optimizing cache management and reducing lock acquisition and release overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If data objects are added to the least recently used list for all workloads, then cache management is simplified, but CPU consumption increases and lock contention worsens

Engineering Contradiction:
Improvecache management complexityVSAvoidCPU consumption
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent segments the workload into sequential and non-sequential categories, applying different cache management strategies to each. For sequential workloads, data objects are processed without being added to the LRU list, avoiding unnecessary CPU operations and lock acquisitions. For non-sequential workloads, the traditional LRU list approach is maintained. This segmentation resolves the contradiction by eliminating unnecessary operations for sequential workloads while preserving the simplified management approach where applicable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts cache management behavior based on workload type identification. The system transitions between two modes: adding data objects to the LRU list for non-sequential workloads and bypassing the LRU list for sequential workloads. This dynamic adaptation allows the system to optimize CPU consumption and lock contention based on the specific characteristics of each workload, resolving the contradiction between simplified management and reduced resource usage.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If data objects are added to the least recently used list, then cache recall functionality is enabled, but lock acquisition and release overhead increases

Engineering Contradiction:
Improvecache recall capabilityVSAvoidlock overhead time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent segments cache management operations based on workload type, applying LRU list operations only to non-sequential workloads that benefit from cache recall functionality. Sequential workloads bypass the LRU list entirely, eliminating lock overhead without impacting functionality where recall is not needed. This selective application resolves the contradiction by enabling cache recall only when beneficial.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the LRU list operation from the universal cache management process and applies it selectively only to non-sequential workloads. By removing the LRU list addition step for sequential workloads, the system eliminates unnecessary lock acquisition and release operations, reducing time loss while preserving cache recall capability where it provides value.

Inventive Principle:
Principle #2Taking out (Extraction)

3Speed

If cache stores data objects for all workloads, then I/O performance is improved, but storage space efficiency decreases

Engineering Contradiction:
ImproveI/O performanceVSAvoidstorage space utilization
Core Design Contradiction:
SpeedVSQuantity of substance

Solution Approach 1:

The patent segments cache space management based on workload type, allocating cache resources differently for sequential and non-sequential workloads. For sequential workloads, the system processes data objects without storing them in the LRU list, freeing up cache space. For non-sequential workloads, the traditional caching approach is maintained. This segmentation improves storage space efficiency while preserving I/O performance benefits where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent discards the practice of adding sequential workload data objects to the LRU list, thereby recovering cache storage space that would otherwise be consumed by these objects. The system recovers space by bypassing the LRU list operation for sequential workloads, improving storage space utilization while maintaining I/O performance through alternative processing paths.

Inventive Principle:
Principle #34Discarding and recovering

Data Source

PatentUS9846655B1Managing processing tasks in storage systems
Publication Date: 2017.12.19 EMC IP HLDG CO LLC
  • US9846655B1 patent drawing
  • US9846655B1 patent drawing
  • US9846655B1 patent drawing

AI summary

A method is used in managing processing tasks in storage systems. A set of tasks is received for processing. A type of the set of tasks is identified. Based on the type of the set of tasks, a determination is made as to whether to add data objects associated with the set of tasks to a used object list managed in conjunction of a cache of the system for accessing the data objects associated with the set of tasks. The cache is configured to store the data objects of the storage system. A portion of a memory of the storage system is reserved as the cache.