Method and apparatus for adaptive page migration and pinning for oversubscribed irregular applications

A method of managing data during execution of an application in a system that includes a host memory, a near memory, and a near device associated with the near memory, wherein the application uses a working set of data that is distributed between a far memory and the near memory, the method comprising:

• counting a number of times that the near device accesses unit of the working set of data from the far memory;
• determining whether the number of times exceeds a dynamically changing access counter threshold, wherein the dynamically changing access counter threshold is, in cases of oversubscription of the near memory, calculated dynamically based on a static threshold that is set for the system, a number of roundtrips of a given data size during the execution of the application, and a multiplicative migration penalty;
• and
• responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrating the unit of data from the far memory to the near memory.

A method of managing data during execution of an application in a system that includes a host memory, a near memory, and a near device associated with the near memory, wherein the application uses a working set of data that is distributed between a far memory and the near memory, the method comprising:

• counting a number of times that the near device accesses a unit of the working set of data from the far memory;
• determining whether the number of times exceeds a dynamically changing access counter threshold, wherein the unit of the working set of data is a page, and wherein the dynamically changing access counter threshold (td) is determined based on the following equation:
• t
• d
• =
• {
• t
• s
• *
• Num
• .
• ⁢
• of
• ⁢
• ⁢
• allocated
• ⁢
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• pages
• Total
• ⁢
• ⁢
• num
• .
• ⁢
• of
• ⁢
• ⁢
• pages
• +
• 1
• ,
• if
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• no
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• oversubscription
• t
• s
• *
• (
• r
• +
• 1
• )
• *
• p
• ,
• otherwise
• where ts=a static threshold that is set for the system, r=a number of roundtrips of a given data size during the execution of the application, Num. of allocated pages is a number of pages allocated to the near device, Total num. of pages is the capacity of the near device, and p=a multiplicative migration penalty;
• and
• responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrating the unit of data from the far memory to the near memory.

A system for executing an application, comprising:

• a near device;
• a near memory coupled to the near device;
• and
• a far memory coupled to the near memory;
• wherein the near device is configured to execute the application using a working set of data in a condition where the working set of data is distributed between the near memory and the far memory, and wherein the system is configured for:
• counting a number of times that the near device accesses a unit of the working set of data from the far memory;
• determining whether the number of times exceeds a dynamically changing access counter threshold, wherein the dynamically changing access counter threshold is, in cases of no oversubscription of the near memory, calculated dynamically based on a static threshold that is set for the system and a current percentage occupancy of the near memory;
• and
• responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrating the unit of data from the far memory to the near memory.

A system for executing an application, comprising:

• a near device;
• a near memory coupled to the near device;
• and
• a far memory coupled to the near memory;
• wherein the near device is configured to execute the application using a working set of data in a condition where the working set of data is distributed between the near memory and the far memory, and wherein the system is configured for:
• counting a number of times that the near device accesses a unit of the working set of data from the far memory;
• determining whether the number of times exceeds a dynamically changing access counter threshold, wherein the dynamically changing access counter threshold is, in cases of oversubscription of the near memory, calculated dynamically based on a static threshold that is set for them system, number of roundtrips of a given data size during the execution of the application, and a multiplicative migration penalty;
• and
• responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrating the unit of data from the far memory to the near memory.

A system for executing an application, comprising:

• a near device;
• a near memory coupled to the near device;
• and
• a far memory coupled to the near memory;
• wherein the near device is configured to execute the application using a working set of data in a condition where the working set of data is distributed between the near memory and the far memory, and wherein the system is configured for:
• counting a number of times that the near device accesses a unit of the working set of data from the far memory;
• determining whether the number of times exceeds a dynamically changing access counter threshold, wherein the unit of the working set of data is a page, and wherein the dynamically changing access counter threshold (td) is determined based on the following equation:
• t
• d
• =
• {
• t
• s
• *
• Num
• .
• ⁢
• of
• ⁢
• ⁢
• allocated
• ⁢
• ⁢
• pages
• Total
• ⁢
• ⁢
• num
• .
• ⁢
• of
• ⁢
• ⁢
• pages
• +
• 1
• ,
• if
• ⁢
• ⁢
• no
• ⁢
• ⁢
• oversubscription
• t
• s
• *
• (
• r
• +
• 1
• )
• *
• p
• ,
• otherwise
• where ts=a static threshold that is set for the system, r=a number of roundtrips of a given data size during the execution of the application, Num. of allocated pages is a number of pages allocated to the near device, Total num. of pages is the capacity of the near device, and p=a multiplicative migration penalty;
• and
• responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrating the unit of data from the far memory to the near memory.

An apparatus for use in a system for executing an application, wherein the application uses a working set of data, and wherein the working set of data is distributed between a near memory and a far memory that are coupled to one another, the apparatus comprising:

• a processing unit configured to:
• (i) count a number of times that a near device accesses a unit of the working set of data from the far memory;
• (ii) determine whether the number of times exceeds a dynamically changing access counter threshold wherein the dynamically changing access counter threshold is, in cases of no oversubscription of the near memory, calculated dynamically based on a static threshold that is set for the system and a current percentage occupancy of the new memory;
• and (iii) responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrate the unit of data from the far memory to the near memory.

An apparatus for use in system for executing an application, wherein the application uses a working set of data, and wherein the working set of data is distributed between a near memory and a far memory that are coupled to one another, the apparatus comprising:

• a processing unit configure to:
• (i) count a number of times that a near device accesses a unit of the working set of data from the far memory;
• (ii) determine whether the number of times exceeds a dynamically changing access counter threshold, wherein the dynamically changing access counter threshold is, in cases of oversubscription of the near memory, calculated dynamically based on a static threshold that is set for the system, a number of roundtrips of a given data size during the execution of the application, and a multiplicative migration penalty;
• and (iii) responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrate the unit of data from the far memory to the near memory.

An apparatus for use in a system for executing an application, wherein the application uses a working set of data, and wherein the working set of data is distributed between a near memory and a far memory that are coupled to one another, the apparatus comprising:

• a processing unit configured to:
• (i) count a number of times that a near device accesses a unit of the working set of data from the far memory;
• (ii) determine whether the number of times exceeds a dynamically changing access counter threshold, wherein the unit of the working set of data is a page, and wherein the dynamically changing access counter threshold (td) is determined based on the following equation:
• t
• d
• =
• {
• t
• s
• *
• Num
• .
• ⁢
• of
• ⁢
• ⁢
• allocated
• ⁢
• ⁢
• pages
• Total
• ⁢
• ⁢
• num
• .
• ⁢
• of
• ⁢
• ⁢
• pages
• +
• 1
• ,
• if
• ⁢
• ⁢
• no
• ⁢
• ⁢
• oversubscription
• t
• s
• *
• (
• r
• +
• 1
• )
• *
• p
• ,
• otherwise
• where ts=a static threshold that is set for the system, r=a number of roundtrips of a given data size during the execution of the application, Num. of allocated pages is a number of pages allocated to the near device, Total num. of pages is the capacity of the near device, and =a multiplicative migration penalty;
• and (iii) responsive to determining that the number of times exceeds the dynamically changing access counter threshold, migrate the unit of data from the far memory to the near memory.