Method for executing a query instruction for idle time accumulation among cores in a multithreading computer system

Patent metadata

Field	Value
Publication number	US-9594661-B2
Application number	US-201514828795-A
Country	US
Kind code	B2
Filing date	Aug 18, 2015
Priority date	Mar 27, 2014
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

Embodiments relate to idle time accumulation in a multithreading computer system. According to one aspect, a computer-implemented method for idle time accumulation in a computer system is provided. The computer system includes a configuration having a plurality of cores and an operating system (OS)-image configurable between 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 method 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.

First claim

What is claimed is:

1. A computer-implemented method for idle time accumulation in a computer system comprising a configuration that comprises 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, the 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; and
obtaining, 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; and
based 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.

2. The method according to claim 1 , wherein the query instruction specifies a location for storing the maximum thread identification value, the multithreading idle time values, and the total-dispatch times.

3. The method according to claim 1 , further comprising a plurality of configurations with logical partitions, each of the logical partitions comprising an OS-image and one or more cores, wherein the query instruction obtains: the maximum thread identification value for each of the logical partitions, the multithreading idle time values for each of the cores within each of the logical partitions, and the total-dispatch times for each of the cores within each of the logical partitions.

4. The method according to claim 3 , further comprising:
calculating an opportunity ratio as a combination of the MT-disabled missed opportunity values and the MT-enabled missed opportunity values for all of the logical partitions divided by the total-dispatch times for all of the logical partitions scaled by the maximum number of threads supported per core by hardware of the computer system.

5. The method according to claim 1 , wherein the maximum thread identification value is used to determine whether the logical partition is in the ST mode or the MT mode.

6. The method according to claim 1 , further comprising:
maintaining the multithreading idle time values on a per thread basis by detecting and accounting for an invalid state or changes to enablement of a wait state;
accumulating, by a hypervisor, an aggregate amount of idle time for each core; and
providing the aggregate amount of idle time for each core as accumulated to the OS-image.

Assignees

• IBM

Inventors

• Bradbury Jonathan D
• Busaba Fadi Y
• Farrell Mark S
• Gainey Jr Charles W
• Greiner Dan F
• Heller Lisa Cranton
• Kubala Jeffrey P
• Osisek Damian L
• Schmidt Donald W
• Slegel Timothy J

Classifications

• G06F1/14

  Time supervision arrangements, e.g. real time clock · CPC title

• G06F9/3851

  from multiple instruction streams, e.g. multistreaming · CPC title

• G06F9/4887

  involving deadlines, e.g. rate based, periodic · CPC title

• G06F9/45533 Primary

  Hypervisors; Virtual machine monitors · CPC title

• G06F9/5077

  Logical partitioning of resources; Management or configuration of virtualized resources (specific details on emulation or internal functioning of virtual machines G06F9/455) · CPC title