Cisco CloudCenter: Get the Hybrid IT Advantage

Cache Coherence

Definition - What does Cache Coherence mean?

Cache coherence is the regularity or consistency of data stored in cache memory. Maintaining cache and memory consistency is imperative for multiprocessors or distributed shared memory (DSM) systems. Cache management is structured to ensure that data is not overwritten or lost. Different techniques may be used to maintain cache coherency, including directory based coherence, bus snooping and snarfing. To maintain consistency, a DSM system imitates these techniques and uses a coherency protocol, which is essential to system operations. Cache coherence is also known as cache coherency or cache consistency.

Techopedia explains Cache Coherence

The majority of coherency protocols that support multiprocessors use a sequential consistency standard. DSM systems use a weak or release consistency standard. The following methods are used for cache coherence management and consistency in read/write (R/W) and instantaneous operations: Written data locations are sequenced. Write operations occur instantaneously. Program order preservation is maintained with RW data. A coherent memory view is maintained, where consistent values are provided through shared memory. Several types of cache coherency may be utilized by different structures, as follows: Directory based coherence: References a filter in which memory data is accessible to all processors. When memory area data changes, the cache is updated or invalidated. Bus snooping: Monitors and manages all cache memory and notifies the processor when there is a write operation. Used in smaller systems with fewer processors. Snarfing: Self-monitors and updates its address and data versions. Requires large amounts of bandwidth and resources compared to directory based coherence and bus snooping.
Share this:

Connect with us

Email Newsletter

Join thousands of others with our weekly newsletter

The 4th Era of IT Infrastructure: Superconverged Systems
The 4th Era of IT Infrastructure: Superconverged Systems:
Learn the benefits and limitations of the 3 generations of IT infrastructure – siloed, converged and hyperconverged – and discover how the 4th...
Approaches and Benefits of Network Virtualization
Approaches and Benefits of Network Virtualization:
Businesses today aspire to achieve a software-defined datacenter (SDDC) to enhance business agility and reduce operational complexity. However, the...
Free E-Book: Public Cloud Guide
Free E-Book: Public Cloud Guide:
This white paper is for leaders of Operations, Engineering, or Infrastructure teams who are creating or executing an IT roadmap.
Free Tool: Virtual Health Monitor
Free Tool: Virtual Health Monitor:
Virtual Health Monitor is a free virtualization monitoring and reporting tool for VMware, Hyper-V, RHEV, and XenServer environments.
Free 30 Day Trial – Turbonomic
Free 30 Day Trial – Turbonomic:
Turbonomic delivers an autonomic platform where virtual and cloud environments self-manage in real-time to assure application performance.