Method and apparatus for allocating memory for immutable data on a computing device

• US 9,477,588 B2
• Filed: 05/07/2014
• Issued: 10/25/2016
• Est. Priority Date: 06/10/2008
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Pliss, Oleg A., Long, Dean R. E., Landau, Erez
• Primary Examiner(s): Yi, David X
• Assistant Examiner(s): Mercado, Ramon A
• Application Number:
  US14/272,234
• Publication Number:
  US 20140244963A1
• Time in Patent Office: 902 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0223 User address space allocation, e.g. contiguous or non contiguous base addressing
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/121 using replacement algorithms
• CPC Class Codes: G06F 2212/1044 Space efficiency improvement

Abstract

A system that allocates memory for immutable data on a computing device. The system allocates a memory region on the computing device to store immutable data for an executing application. This memory region is smaller than the immutable data for the application. When the system subsequently receives a request to access a block of immutable data for the application, the system allocates space in this memory region for the block, and proceeds to load the block into the memory region. If at a later time the space occupied by this first block is needed for another block, the system unloads and discards the first block. If a subsequent operation needs to use information in the first block, the system regenerates the block by transforming raw data associated with the block into a form that can be directly accessed by the application, and then reloads the block into the memory region.

Claims

1. A method comprising:

allocating a memory region on a computing device to store blocks of immutable data on a computing device, wherein the immutable data as a whole does not fit in the memory region and wherein a table of block descriptors maintains one or more currently-used block descriptor entries that each comprise statistical information for one of the blocks and a function pointer that points to a function for regenerating the data in an immutable block that is referenced by the block descriptor entry; and

while executing an application on the computing device, in response to a request to access a particular block of the immutable data that is not already present in the memory region,

determining whether space is available in the memory region to store the particular block,

in response to determining that there is not enough space available in the memory region to store the particular block, using statistical information for the blocks that are stored in the memory region to identify a target block that is unlikely to be accessed before others of the blocks that are stored in the memory region, and evicting the target block from the memory region, wherein the statistical information for the blocks comprises statistical information for the target block that is retrieved from a block descriptor entry that is associated with the target block,

allocating space for the particular block of the immutable data in the memory region,

loading the particular block of the immutable data into the allocated space, and

accessing the particular block of the immutable data from the allocated space in the memory region.

2. The method of claim 1, wherein loading the particular block of the immutable data into the memory region includes:

accessing raw data associated with the particular block of the immutable data;

performing a set of operations on the raw data to transform the raw data into a form that can be accessed directly by the application; and

storing the transformed data into the allocated space for the particular block of the immutable data in the memory region.

3. The method of claim 2, wherein the method further comprises:

upon compiling the application, creating a function that performs the set of operations on the raw data; and

calling the function when loading and re-loading a given block of immutable data into the memory region.

4. The method of claim 1, wherein when an evicted block needs to be accessed again, the method further comprises regenerating the evicted block by transforming raw data associated with the evicted block into a form that can be directly accessed by the application and reloading the regenerated block into the memory region.

5. The method of claim 1, wherein the method further comprises:

detecting an attempt to write to the particular block of the immutable data; and

after the attempt is detected, preventing the particular block of the immutable data from being unloaded from the memory region.

6. The method of claim 1, wherein the statistical information for the blocks in the memory region includes least-recently used (LRU) information for the blocks.

7. The method of claim 1, wherein the statistical information for the blocks is provided by one or more of:

a code library;

the application;

or

an operating system for the computing device.

8. The method of claim 1, wherein the immutable data includes executable application instructions as well as data that is read from and written to by executable application instructions.

9. The method of claim 1, wherein the method further comprises dynamically adjusting a size of the memory region while executing the application based on memory requirements of the application.

10. One or more non-transitory computer-readable storage media storing instructions that when executed by a computer cause the computer to perform a method comprising:

allocating a memory region on a computing device to store blocks of immutable data on a computing device, wherein the immutable data as a whole does not fit in the memory region and wherein a table of block descriptors maintains one or more currently-used block descriptor entries that each comprise statistical information for one of the blocks and a function pointer that points to a function for regenerating the data in an immutable block that is referenced by the block descriptor entry; and

while executing an application on the computing device, in response to a request to access a particular block of the immutable data that is not already present in the memory region,

determining whether space is available in the memory region to store the particular block,

in response to determining that there is not enough space available in the memory region to store the particular block, using statistical information for the blocks that are stored in the memory region to identify a target block that is unlikely to be accessed before others of the blocks that are stored in the memory region, and evicting the target block from the memory region, wherein the statistical information for the blocks comprises statistical information for the target block that is retrieved from a block descriptor entry that is associated with the target block,

allocating space for the particular block of the immutable data in the memory region,

loading the particular block of the immutable data into the allocated space, and

accessing the particular block of the immutable data from the allocated space in the memory region.

11. The one or more non-transitory computer-readable storage media of claim 10, wherein loading the particular block of the immutable data into the memory region includes:

accessing raw data associated with the particular block of the immutable data;

performing a set of operations on the raw data to transform the raw data into a form that can be accessed directly by the application; and

storing the transformed data into the allocated space for the particular block of the immutable data in the memory region.

12. The one or more non-transitory computer-readable storage media of claim 11, wherein the method further comprises:

upon compiling the application, creating a function that performs the set of operations on the raw data; and

calling the function when loading and re-loading the particular block of immutable data into the memory region.

13. The one or more non-transitory computer-readable storage media of claim 10, wherein when an evicted block needs to be accessed again, the method further comprises regenerating the evicted block by transforming raw data associated with the evicted block into a form that can be directly accessed by the application and reloading the regenerated block into the memory region.

14. The one or more non-transitory computer-readable storage media of claim 10, wherein the method further comprises:

detecting an attempt to write to the particular block of the immutable data; and

after the attempt is detected, preventing the particular block of the immutable data from being unloaded from the memory region.

15. The one or more non-transitory computer-readable storage media of claim 10, wherein the statistical information for the blocks is provided by one or more of:

a code library;

the application;

or

an operating system for the computing device.

16. The one or more non-transitory computer-readable storage media of claim 10, wherein the method further comprises dynamically adjusting a size of the memory region while executing the application based on memory requirements of the application.

17. An apparatus that allocates memory for immutable data on a computing device, comprising:

a processor;

a memory; and

a computer-readable storage medium comprising instructions that, when executed by the processor, instantiate;

an allocation mechanism configured to allocate a memory region on the computing device to store blocks of immutable data on a computing device, wherein the immutable data as a whole does not fit in the memory region and wherein a table of block descriptors maintains one or more currently-used block descriptor entries that each comprise statistical information for one of the blocks and a function pointer that points to a function for regenerating the data in an immutable block that is referenced by the block descriptor entry;

an execution mechanism configured to execute an application; and

while executing an application on the computing device, in response to a request to access a particular block of the immutable data that is not already present in the memory region, the execution mechanism is configured to,

determine whether space is available in the memory region to store the particular block,

in response to determining that there is not enough space available in the memory region to store the particular block, use statistical information for the blocks that are stored in the memory region to identify a target block that is unlikely to be accessed before others of the blocks that are stored in the memory region, and evict the target block from the memory region, wherein the statistical information for the blocks comprises statistical information for the target block that is retrieved from a block descriptor entry that is associated with the target block,

allocate space for the particular block of the immutable data in the memory region,

load the particular block of the immutable data into the allocated space, and

access the particular block of the immutable data from the allocated space in the memory region.

18. The apparatus of claim 17, wherein while loading the particular block of the immutable data into the memory region, the execution mechanism is configured to:

access raw data associated with the particular block of the immutable data;

perform a set of operations on the raw data to transform the raw data into a form that can be accessed directly by the application; and

store the transformed data into the allocated space for the particular block of the immutable data in the memory region.

19. The apparatus of claim 18, further comprising:

a compiler, wherein upon compiling the application, the compiler is configured to create a function that performs the set of operations on the raw data; and

wherein the execution mechanism is configured to call the function when loading and re-loading a given block of immutable data into the memory region.