Using Virtual CPU Migration to Solve the Lock Holder Preemption Problem in a Multicore Processor-Based Virtualization Layer for Embedded Systems

When a real-time OS (RTOS) and a symmetric multiprocessing general purpose OS (SMP GPOS) are executed on the same multicore processor, there is a possibility to cause the lock holder preemption (LHP) problem, which is a well known problem of the sources of the performance degradation on an SMP GPOS. The problem occurs when a kernel mode thread holding a lock in a SMP GPOS is preempted by other OSes if these OSes share the same physical core. The existing solution does not take into account real-time responsiveness so it is not suitable to use in embedded systems. The paper proposes two new techniques to avoid the LHP problem for ensuring both the real-time responsiveness of real-time OS and the high throughput of SMP GPOS. The new proposed techniques have been implemented on our virtualization layer called SPUMONE, and we measured the results showing that the proposed new techniques reduce the LHP problem without degrading the real-time responsiveness.