US 5,317,754 AGranted

Method and apparatus for enabling an interpretive execution subset

AssigneeInternational Business Machines Corporation

InventorsGeoffrey O. Blandy, Lisa C. Heller, Robert E. Murray

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Abstract

An apparatus and method are established for recognizing guest virtual machines which require only a subset of interpretive execution facilities. The interpretive execution initialization process recognizes subset candidates and bypasses initialization of those facilities not required by the candidates. The candidates are typically short duration jobs and a reduction of initialization and termination overhead creates a substantial performance improvement. The translation lookaside buffer operation is modified to flag subset guest entries as host entries and to associate a unique segment table origin with each subset guest. This allows the TLB entries to remain between guest machine dispatches eliminating TLB purge time and allowing potential reuse of TLB entries if the same guest is repeatedly dispatched within a short time period. The guest machine state description is modified to flag subset candidates based on address translation and timing requirements. Initialization of timing facilities is bypassed in certain subset modes further reducing initialization overhead.

Claims5

Dependent claims

A method of operating virtual machines (VMs) in a data processing system having one or more processors and an electronic storage, a host control program (host) overseeing the system and all VMs in the system, each VM having an associated quest control program (quest) using interpretive execution means on a processor in the system, the method comprising the steps of:

requesting the host to initiate a process for establishing interpretive execution by a VM on a processor,
testing by the process for an indication associated with the VM for indicating whether the VM has a subset state,
bypassing specified steps in the process if the testing step detects the subset state, but executing the specified steps if the testing step does not detect the subset state,
structuring the content of the state description to include a subset indication of whether the process can bypass code for controlling a VM associated with the state description, and the state description further including one or more of bypass-defining indicators including a first indicator to control bypassing a first set of specified steps in the process for providing one function for the VM, and a second indicator to control bypassing a second set of specified steps in the process for controlling another function for the VM, and
structuring the first indicator to control bypassing a set of specified steps in the process that provide dynamic address translation for the VM, and structuring the second indicator to control bypassing another set of specified steps in the process that control a timing facility in the system.

2 more elements

requesting the host to initiate a process for establishing interpretive execution by a VM on a processor,
testing by the process for an indication associated with the VM for indicating whether the VM has a subset state,
bypassing specified steps in the process if the testing step detects the subset state, but executing the specified steps if the testing step does not detect the subset state,
structuring the content of the state description to include:
a subset indication of whether the process can bypass code for controlling a VM associated with the state description, and the state description further including one or more bypass-defining indicators including a first indicator to control bypassing a first set of specified steps in the process for providing one function for the VM, and a second indicator to control bypassing a second set of specified steps in the process for controlling another function for the VM,
controlling virtual addressing by the host control program by a state of a host dynamic address translation (DAT) indicator, and controlling virtual addressing by each guest control program by a state of a guest DAT indicator for each guest in a state description associated with the guest,
translating host virtual addresses if the host DAT indicator is set on, and translating guest virtual addresses if the guest DAT indicator is set on in an associated state description,
storing virtual address translations of the host and guests executing in a processor by using a hardware translation lookaside buffer (TLB) in the processor for containing an entry for each address translation recently performed in the processor, and
purging the contents of the TLB for a VM being established by the process if the VM has an associated subset state set on in an associated state description and a last previous guest dispatched on the processor does not have an associated subset state set on in an associated state description.

6 more elements

Dependencies are inferred from the claim text.