What is synchronized multithreading in the CPU

Synchronous Multithreading (SMT) is a hardware multithreading technology that can execute instructions from multiple threads during a CPU's clock cycle. In essence, synchronous multithreading is a way of translating thread-level parallel processing (multiple CPUs) into instruction-level parallel processing (the same CPU). Synchronous multithreading is the ability of a single physical processor to assign instructions simultaneously from multiple hardware thread contexts. Synchronous multithreading is used in business environments and for cycles/directives (CPI) to count higher workload creative energy advantages. The processor uses superscalar structure and is best suited to read and run instructions in parallel. Synchronous multithreading allows you to schedule two applications simultaneously on the same processor, thereby leveraging the processor's superscalar structure.

Overview

No single application can fully load the processor. When a thread encounters a long wait-time event, synchronous multithreading allows instructions in another thread to use all the execution units. For example, when a thread has cache misses, another thread can continue to execute. Synchronous multithreading is the function of the power5™ and power6™ processors and can be used in conjunction with shared processors.

SMT can optimize the performance of commercial transaction processing load by up to 30%. SMT is a good choice when you pay more attention to the overall throughput of your system than to the throughput of individual threads.

However, not all applications can achieve performance optimization through SMT. Applications that are performance-constrained, or those that run out of memory bandwidth for all processors, are not performance-enhanced by executing two threads on the same processor.