STABLIZING OPERATION OF AN EMULATED SYSTEM

1 . A method for stabilizing an emulated system, comprising:

executing a first operating system (OS) on an instruction processor of a data processing system, wherein the first OS includes instructions of a first instruction set that are native to the instruction processor;

emulating a second OS and a plurality of application programs on the first OS on the data processing system, wherein the second OS and application programs include instructions of a second instruction set that are not native to the instruction processor;

polling the first OS by the emulated second OS for memory statistics, wherein the memory statistics indicate a current state of operating parameters of the memory of the data processing system used by the first OS in managing the data processing system; and

controlling a number of the application programs allowed to execute by the second OS in response to the memory statistics provided by the first OS to the second OS.

2 . The method of claim 1 , wherein the controlling includes denying initiation of execution of an additional application program beyond currently executing ones of the plurality of application programs.

3 . The method of claim 1 , wherein the controlling includes terminating execution of one or more of currently executing ones of the plurality of application programs.

4 . The method of claim 3 , wherein the terminated one or more application programs is an interactive program, the method further comprising:

after the terminating step, requesting by the emulated second OS to the first OS for the first OS to provide the memory statistics, and determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable; and

in response to the current state of the operating parameters being unacceptable, repeating the terminating and requesting steps until the current state of the operating parameters is acceptable.

5 . The method of claim 4 , wherein the terminating and requesting steps are repeated until there is no interactive program available to terminate.

6 . The method of claim 5 , wherein at least one currently executing application program is a batch program, the method further comprising:

in response to the current state of the operating parameters being unacceptable and there being no interactive program available to terminate, the terminating step terminates execution of at least one currently executing batch program.

7 . The method of claim 3 , wherein the plurality of application programs include interactive programs and batch programs, wherein the terminating includes selecting interactive programs for termination before selecting batch programs for termination.

8 . The method of claim 1 , further comprising:

determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable; and

wherein the controlling includes,

denying initiation of execution of an additional application program beyond currently executing ones of the plurality of application programs in response to the current state being unacceptable, and

allowing initiation of execution of an additional application program beyond currently executing ones of the plurality of application programs in response to the current state being acceptable.

9 . The method of claim 1 , further comprising:

determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable; and

in response to the current state being unacceptable, returning by the second OS to the first OS, memory that is allocated to the second OS and that the second OS has not allocated to any of the plurality of application programs.

10 . An emulation system, comprising:

a data processing system including at least one instruction processor coupled to a memory;

a first operating system (OS) executing on the at least one instruction processor, wherein the first OS includes instructions of a first instruction set that are native to the instruction processor;

means for emulating a second OS and a plurality of application programs on the first OS, wherein the second OS and application programs include instructions of a second instruction set that are not native to the instruction processor;

means for periodically requesting by the emulated second OS for memory statistics from the first OS, wherein the memory statistics indicate a current state of operating parameters of the memory of the data processing system used by the first OS in managing the data processing system; and

means for limiting execution of the application programs by the second OS in response to the memory statistics provided by the first OS to the second OS.

11 . An emulation system, comprising:

a data processing system including at least one instruction processor coupled to a memory, and a first operating system (OS) executing on the at least one instruction processor, wherein the first OS includes instructions of a first instruction set that are native to the instruction processor;

an instruction processor emulator executable on the at least one instruction processor, wherein the instruction processor emulator emulates execution of instructions of a second instruction set that are not native to the at least one instruction processor;

a second OS and a plurality of application programs emulated on the instruction processor emulator, wherein the second OS and application programs include instructions of a second instruction set that are not native to the instruction processor;

wherein the second OS executes program code that performs the steps including,

periodically requesting memory statistics from the first OS, wherein the memory statistics indicate a current state of operating parameters of the memory of the data processing system used by the first OS in managing the data processing system;

determining whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable;

selecting, in response to the current state being unacceptable, between terminating one or more of the plurality of application programs and returning to the first OS memory that is allocated to the second OS; and

performing the selected one of terminating one or more application programs and freeing memory.

12 . The emulation system of claim 1 , wherein the selecting includes selecting between denying initiation of execution of an additional application program beyond currently executing ones of the plurality of application programs, terminating one or more of the plurality of application programs and returning to the first OS memory that is allocated to the second OS.

13 . The emulation system of claim 12 , wherein the terminated one or more application programs is an interactive program, the steps further including,

after the terminating step, requesting by the emulated second OS to the first OS for the first OS to provide the memory statistics, and determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable; and

in response to the current state of the operating parameters being unacceptable, repeating the terminating and requesting steps until the current state of the operating parameters is acceptable.

14 . The emulation system of claim 13 , wherein the terminating and requesting steps are repeated until there is no interactive program available to terminate.

15 . The emulation system of claim 14 , wherein at least one currently executing application program is a batch program, the steps further including, in response to the current state of the operating parameters being unacceptable and there being no interactive program available to terminate, the terminating step terminates execution of at least one currently executing batch program.

16 . The emulation system of claim 12 , wherein the plurality of application programs include interactive programs and batch programs, wherein the terminating includes selecting interactive programs for termination before selecting batch programs for termination.

17 . The emulation system of claim 11 , the steps further including,

determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable;

denying initiation of execution of an additional application program beyond currently executing ones of the plurality of application programs in response to the current state being unacceptable, and

allowing initiation of execution of an additional application program beyond currently executing ones of the plurality of application programs in response to the current state being acceptable.

18 . The emulation system of claim 11 , the steps further including,

determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable, and

in response to the current state being unacceptable, returning by the second OS to the first OS, memory that is allocated to the second OS and that the second OS has not allocated to any of the plurality of application programs.

19 . The emulation system of claim 11 , wherein the terminated one or more application programs is an interactive program, the steps further including,

after the terminating step, requesting by the emulated second OS to the first OS for the first OS to provide the memory statistics, and determining by the second OS whether the current state of operating parameters indicated by the memory statistics is acceptable or unacceptable, and

in response to the current state of the operating parameters being unacceptable, repeating the terminating and requesting steps until the current state of the operating parameters is acceptable.

20 . The emulation system of claim 19 , wherein the terminating and requesting steps are repeated until there is no interactive program available to terminate.