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

• US 9,594,661 B2
• Filed: 08/18/2015
• Issued: 03/14/2017
• Est. Priority Date: 03/27/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bradbury, Jonathan D., Busaba, Fadi Y., Farrell, Mark S., Gainey, Charles W. Jr., Greiner, Dan F., Heller, Lisa Cranton, Kubala, Jeffrey P., Osisek, Damian L., Schmidt, Donald W., Slegel, Timothy J.
• Primary Examiner(s): Huisman, David J
• Application Number:
  US14/828,795
• Publication Number:
  US 20150355940A1
• Time in Patent Office: 574 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• CPC Class Codes: G06F 11/302 where the computing system component is a software system
• CPC Class Codes: G06F 11/3024 where the computing system component is a central processing unit [CPU]
• CPC Class Codes: G06F 11/3423 where the assessed time is active or idle time
• CPC Class Codes: G06F 11/3442 for planning or managing the needed capacity
• CPC Class Codes: G06F 2201/865 Monitoring of software
• CPC Class Codes: G06F 9/30076 to perform miscellaneous control operations, e.g. NOP
• CPC Class Codes: G06F 9/30145 Instruction analysis, e.g. decoding, instruction word fields
• CPC Class Codes: G06F 9/3851 from multiple instruction streams, e.g. multistreaming
• CPC Class Codes: G06F 9/45533 Hypervisors; Virtual machine monitors
• CPC Class Codes: G06F 9/46 Multiprogramming arrangements
• CPC Class Codes: G06F 9/4887 involving deadlines, e.g. rate based, periodic
• CPC Class Codes: G06F 9/5077 Logical partitioning of resources; Management or configuration of virtualized resources specific details on emulation or internal functioning of virtual machines G06F9/455

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.

Claims

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.