MIPS® MT ASE

• Multi-threading is an execution model that is geared towards maximizing throughput within a system
• Allows multiple software threads to consume all execution and memory bandwidth instead of stalling within one software thread
• Two MT modes supported:
  • Multiple Virtual Processors, which allows multiple operating systems to be simultaneously running on physical CPU
  • Multiple Thread Contexts, in which multiple threads of a single software process can be simultaneously running on one physical CPU
• Quality of service (QoS) scheduling satisfies real-time requirements
• Threads are relocate-able in multi-core systems
• Immediate system throughput boost of 20-40% with little or no code changes

• TCs (Thread Context) replicate user-mode state such as the general purpose registers
• VPEs (Virtual Processor Elements) replicate privileged-mode state such as the TLB and status registers pertaining to interrupts
• Multiple TCs can be assigned to any VPE
• Switching among runnable threads is handled by hardware
  • Fine-grained switching between threads is possible, including switching every CPU cycle
  • Thread switching policy is totally customer defined - can be round-robin, weighted-round-robin, priority-driven, etc.
• Software controls the creation as well as the suspension of runnable threads
• Support for hardware events (such as interrupts) to suspend or wake up threads
• Gating storage can be used as a communications channel between threads - allows for data-driven scheduling of threads
• A thread can be marked as privileged to allow access to another thread's resources
• Interrupt affinity to a specific VPE is supported
• Software control is provided for enabling and disabling of each TC and VPE

v1.05 (705 KB)