Methods and devices for reducing compressed page loading time on page fault
Exemplary embodiments provide for compressing, storing, retrieving and decompressing paged code from mass storage devices. By evaluating the size of compressed virtual pages relative to the storage page (read unit) of the mass storage device into which the compressed virtual pages are to be stored, decisions can be made which facilitate later read out and decompression of those compressed virtual pages. According to exemplary embodiments, a virtual page can be stored uncompressed, compressed but undivided or compressed and subdivided into a plurality of parts based on an evaluation.
1. A method for storing a plurality of virtual pages in a mass storage device, the method comprising:
compressing each virtual page to generate a corresponding compressed virtual page having a corresponding compressed size;
evaluating said compressed size of each of said compressed virtual pages relative to a page size of said mass storage device; and
selectively storing each of the plurality of virtual pages in said mass storage device uncompressed, compressed but without subdividing, or subdivided with compressed subparts, in a manner that is based on at least one of: an uncompressed size of the respective virtual page and said compressed size of the respective virtual page, selected based on said evaluating,
wherein, for each one of the plurality of virtual pages that is stored in said mass storage device subdivided with compressed subparts, said storing comprises:
concluding that said compressed size of the one of the plurality of virtual pages will not fit within one page of said mass storage device;
in response to said concluding, dividing the one of the plurality of virtual pages into a plurality of subdivided uncompressed parts of the one of the plurality of virtual pages;
independently performing said compressing, said evaluating, and said selectively storing for each of said plurality of subdivided uncompressed parts of the one of the plurality of virtual pages.
2. The method of claim 1 , further comprising:
padding one of said compressed virtual pages, if needed, to reach a next highest predefined chunk size relative to said compressed size of the one of said compressed virtual pages, to generate a compressed virtual page at said next highest predefined chunk size.
3. The method of claim 1 , further comprising:
storing one or more of the compressed virtual pages in a page of said mass storage device, said compressed virtual pages fitting within said page of said mass storage device, and
padding a remaining storage space in said page of said mass storage device.
4. The method of claim 1 , wherein said storing further comprises:
storing, as uncompressed, said compressed virtual pages for which said corresponding compressed size is equal to said page size of said mass storage device.
5. The method of claim 1 , wherein said storing further comprises:
storing, as compressed but without subdividing, said compressed virtual pages for which said corresponding compressed size is less than or equal to said page size of said mass storage device.
6. The method of claim 1 , further comprising:
storing, in compressed subparts, said compressed virtual pages for which said corresponding compressed size is greater than said page size of said mass storage device.
7. The method of claim 1 , further comprising:
reordering, prior to storing, said uncompressed virtual pages, said compressed virtual pages and said compressed subparts of said virtual pages based on the uncompressed size of the uncompressed virtual pages and the compressed size of the compressed virtual pages and the compressed subparts of said virtual pages.
8. The method of claim 1 , further comprising:
storing, in said mass storage device, a mapping table which includes information regarding where said uncompressed virtual pages, said compressed virtual pages and said compressed subparts of said virtual pages are stored in said mass storage device.
9. An electronic device comprising:
a first memory interface configured to connect at least one mass storage device, a second memory interface configured to connect at least one random access memory (RAM);
a processor configured to execute a memory management function, the memory management function comprising storing a plurality of virtual pages into the at least one mass storage device when said at least one mass storage device is connected to the first memory interface,
wherein said memory management function is configured to: compress each virtual page to generate a corresponding compressed virtual page having a corresponding compressed size;
evaluate said compressed size of each of said compressed virtual pages relative to a page size of said mass storage device; and
selectively store each of the plurality of virtual pages in said mass storage device uncompressed, compressed but without subdividing, or subdivided with compressed subparts, in a manner that is based on at least one of: an uncompressed size of the respective virtual page and said compressed size of the respective virtual page, selected based on said evaluating,
wherein, for each one of the plurality of virtual pages that is stored in said mass storage device subdivided with compressed subparts, said storing comprises:
concluding that said compressed size of the one of the plurality of virtual pages will not fit within one page of said mass storage device;
in response to said concluding, dividing the one of the plurality of virtual pages into a plurality of subdivided uncompressed parts of the one of the plurality of virtual pages;
independently performing said compressing, said evaluating, and said selectively storing for each of said plurality of subdivided uncompressed parts of the one of the plurality of virtual pages.
10. The electronic device of claim 9 , wherein said memory management function is further configured to:
pad one of said compressed virtual pages, if needed, to reach a next highest predefined chunk size relative to said compressed size of the one of said compressed virtual pages, to generate a compressed virtual page at said next highest predefined chunk size.
11. The electronic device of claim 9 , wherein said memory management function is further configured to:
store one or more of the compressed virtual pages in a page of said mass storage device, said compressed virtual pages fitting within said page of said mass storage device, and
pad a remaining storage space in said page of said mass storage device.
12. The electronic device of claim 9 , wherein said storing further comprises:
storing, as uncompressed, said compressed virtual pages for which said corresponding compressed size is equal to said page size of said mass storage device.
13. The electronic device of claim 9 , wherein said storing further comprises:
storing, as compressed but without subdividing, said compressed virtual pages for which said corresponding compressed size is less than or equal to said page size of said mass storage device.
14. The electronic device of claim 9 , wherein said memory management function is further configured to:
store, in compressed subparts, said compressed virtual pages for which said corresponding compressed size is greater than said page size of said mass storage device.
15. The electronic device of claim 9 , wherein said memory management function is further configured to:
reorder, prior to storing, said uncompressed virtual pages, said compressed virtual pages and said compressed subparts of said virtual pages based on the uncompressed size of the uncompressed virtual pages and the compressed size of the compressed virtual pages and the compressed subparts of said virtual pages.
16. The electronic device of claim 9 , wherein said memory management function is further configured to:
store, in said mass storage device, a mapping table which includes information regarding where said uncompressed virtual pages, said compressed virtual pages and said compressed subparts of said virtual pages are stored in said mass storage device.