Sign In

Communications of the ACM

Research highlights

Technical Perspective: Rethinking Caches For Throughput Processors

Caches have been a mainstay of computer design for nearly 50 years and a continued subject of academic and industry research. Caches are intended to capture locality in the instructions or data of a program, enabling a computer system to provide the illusion of a large fast memory, when in fact the underlying hardware only provides physical structures that are small and fast (caches) or large and slow (main memory). CPU systems today have as many as four levels of cache spanning on-chip SRAM to off-chip embedded DRAM.

CPU systems have typically used caches as a means to hide memory latency. Without caching, a single-threaded program would spend the vast majority of its time stalled waiting for data to return from off-chip DRAM memory. However, throughput-oriented computing systems, such as vector processors and GPUs, are able to employ parallelism to tolerate memory latency, reducing the need for the latency reduction effects of a cache. GPUs in particular use massive multithreading to tolerate the latency; when one thread executes a load instruction that accesses main memory, other threads can execute, keeping the processor busy. Instead of being sensitive to memory latency, throughput-oriented systems tend to be sensitive to memory bandwidth. As a result, their memory hierarchies have traditionally been designed to employ caches to reduce DRAM bandwidth demand rather than to reduce latency.


No entries found

Log in to Read the Full Article

Sign In

Sign in using your ACM Web Account username and password to access premium content if you are an ACM member, Communications subscriber or Digital Library subscriber.

Need Access?

Please select one of the options below for access to premium content and features.

Create a Web Account

If you are already an ACM member, Communications subscriber, or Digital Library subscriber, please set up a web account to access premium content on this site.

Join the ACM

Become a member to take full advantage of ACM's outstanding computing information resources, networking opportunities, and other benefits.

Subscribe to Communications of the ACM Magazine

Get full access to 50+ years of CACM content and receive the print version of the magazine monthly.

Purchase the Article

Non-members can purchase this article or a copy of the magazine in which it appears.
Sign In for Full Access
» Forgot Password? » Create an ACM Web Account