Multithreading computer system and program product for executing a query instruction for idle time accumulation among cores

摘要

Embodiments relate to idle time accumulation in a multithreading computer system. According to one aspect, a computer system includes a configuration having a plurality of cores and an operating system (OS)-image configurable between a single thread (ST) mode and a multithreading (MT) mode in a logical partition. The MT mode supports multiple threads on shared resources per core simultaneously. The computer system also includes a multithreading facility configured to perform a method that includes executing a query instruction on an initiating core of the plurality of cores. The executing includes obtaining, by the OS-image, a maximum thread identification value indicating a current maximum thread identifier of the cores within the logical partition. The initiating core also obtains a multithreading idle time value for each of the cores indicating an aggregate amount of idle time of all threads enabled on each of the cores in the MT mode.

主权项

1. A computer system, comprising:
a configuration comprising a plurality of cores and an operating system (OS)-image configurable between a single thread (ST) mode and a multithreading (MT) mode in a logical partition, the MT mode supporting multiple threads on shared resources per core simultaneously; and a multithreading facility circuit of one or more of the cores, the multithreading facility circuit configured to perform a method comprising:
executing a query instruction on an initiating core of the plurality of cores, the executing comprising:
obtaining, by the OS-image, a maximum thread identification value indicating a current maximum thread identifier of the cores within the logical partition;obtaining, by the initiating core, a multithreading idle time value for each of the cores indicating an aggregate amount of idle time of all threads enabled on each of the cores in the MT mode; andobtaining, by the initiating core, a total-dispatch time for each of the cores as an accumulated time that each of the cores was dispatched;based on determining that the logical partition is in the ST mode, determining an MT-disabled missed opportunity value as a sum of the total-dispatch times for all of the cores within the logical partition scaled by one less than a maximum number of threads supported per core by hardware of the computer system; andbased on determining that the logical partition is in the MT mode, determining an MT-enabled missed opportunity value as a sum of the multithreading idle time values for all of the cores within the logical partition.