International Business Machines Corporation

Siwei Lu

Oluwatobi Ajila

Babneet Singh

Hybrid virtual thread context switching in virtual machines is provided. For virtual threads scheduled to run on a VM, it is determined whether a virtual thread requires a stack. If a stack is required, it is determined whether low memory has space to allocate a stack. If there is space, a stack in low memory is allocated. If not, unused stacks are copied from low to high memory. If the virtual thread does not require a stack, it is determined whether the virtual thread stack is in low memory. If it is not, it is copied from high memory if there is enough space in low memory. If there is not enough space, unused stacks are copied from low memory to high memory. If the stack is in low memory, the method performs a stack switch and schedules the virtual on a carrier thread of the VM.

Hybrid virtual thread context switching mechanism

Multiple level stack caching is provided. A user level thread of a multithreaded application is unmounted from a carrier thread of an operating system. An analysis of a level 1 cache corresponding to the carrier thread in memory is performed to determine whether the level 1 cache is full. An analysis of a level 2 cache in memory is performed to determine whether the level 2 cache is full in response to determining that the level 1 cache corresponding to the carrier thread in memory is full. A user level thread stack corresponding to the user level thread is stored in the level 2 cache in memory in response to determining that the level 2 cache in memory is not full.

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Ottawa, Canada

Siwei Lu