Chip Multithreading (CMT)

    Тут (Multithreaded Application Acceleration with Chip Multithreading (CMT), Multicore/Multithread UltraSPAR C® Processors) SUN популярно объясняет, чем вызвано использование CMT и какие дает преимущества на примере VoIP телефонии, поиска строк и антивирусной защиты. Если кратко, то большинство потоков в реальных приложениях заблокированы на операциях доступа к памяти (ОЗУ), имея много потоков на одно ядро можно быстро перебрасывать ресурсы ядра от блокированного потока к неблокированному.
    "Sun Microsystems was the first company to recognize that the speed of data access from memory was the critical bottleneck, and has overcome this problem with the chip multithreading (CMT) architecture that is the basis of the UltraSPARC® T1 and T2 processors."
    "Even if a particular thread stalls while waiting for data to be available from memory, the core can switch immediately to another thread and the pipeline remains continuously active, doing useful work."
    "These simpler pipelines can process a large number of simultaneous threads, rather than running a single thread as quickly as possible."