Method and apparatus for persistently caching storage data in a page cache

1. An apparatus comprising:

a processor comprising circuitry, the processor configured to:

implement a first file system that is to send first data requests towards a volatile page cache;

implement a second file system that is to send second data requests towards a persistent page cache;

identify a request for first data from an application;

determine whether the persistent page cache stores a copy of the first data, wherein the persistent page cache is directly addressable by the processor and is to cache second data of a storage device that is not directly addressable by the processor; and

access the first data from the persistent page cache.

2. The processor of claim 1 , wherein the processor is to:

identify a request for third data from a second application;

determine whether the volatile page cache stores a copy of the third data, wherein the volatile page cache is directly addressable by the processor and is to cache fourth data of the storage device; and

access the third data from the volatile page cache.

3. The processor of claim 1 , wherein the processor is to:

implement a volatile page cache manager that is to determine that a file that includes the first data is marked for caching in the persistent page cache; and

send a request for the first data to a persistent page cache manager.

4. The processor of claim 1 , wherein the first file system is to:

determine whether a file that includes the first data is marked for caching in the persistent page cache or volatile page cache; and

in response to determining that the file is marked for caching in the persistent page cache, send a request for the first data to the second file system.

5. The processor of claim 1 , wherein the processor is to:

implement a shim layer that is to intercept a data request sent to the first file system and communicate the data request to the second file system.

6. The processor of claim 1 , wherein the processor is to determine whether to cache data in the volatile page cache or the persistent page cache based on at least one of:

a hint from an application that issues a system call referencing the data to be cached;

whether the data to be cached is opened for writing;

whether the data to be cached is required for booting; or

whether the data to be cached is file data or metadata.

7. The processor of claim 1 , wherein the processor is to send a request to the storage device to copy the first data to the persistent page cache upon a determination that the persistent page cache does not store a copy of the first data.

8. The processor of claim 7 , wherein the processor is to translate a file descriptor and offset of the request for data into a logical block address and send the logical block address to the storage device in the request to the storage device.

9. The processor of claim 1 , wherein the volatile page cache is to be stored in a volatile memory that is further to store application code and application data.

10. The processor of claim 1 , wherein the processor is to, upon receiving a request to sync dirty data of the persistent page cache, update metadata in the persistent page cache to mark the dirty data as persistent.

11. A non-transitory machine readable storage medium having instructions stored thereon, the instructions when executed by a processor to cause the processor to:

implement a first file system that is to send data requests towards a volatile page cache;

implement a second file system that is to send data requests towards a persistent page cache;

identify a request for first data from an application;

determine whether the persistent page cache stores a copy of the first data, wherein the persistent page cache is directly addressable by the processor and is to cache second data of a storage device that is not directly addressable by the processor; and

access the first data from the persistent page cache.

12. The storage medium of claim 11 , wherein the instructions when executed are to further cause the processor to:

identify a request for third data from a second application;

determine, whether the volatile page cache stores a copy of the third data, wherein the volatile page cache is directly addressable by the processor and is to cache fourth data of the storage device; and

access the third data from the volatile page cache.

13. The storage medium of claim 11 , wherein the instructions when executed are to further cause the processor to:

implement a volatile page cache manager that is to determine that a file that includes the first data is marked for caching in the persistent page cache; and

send a request for the first data to a persistent page cache manager.

14. The storage medium of claim 11 , wherein the instructions when executed are to further cause the processor to implement the first file system of an operating system, wherein the first file system is to:

determine whether a file that includes the first data is marked for caching in the persistent page cache or volatile page cache; and

in response to determining that the file is marked for caching in the persistent page cache, send a request for the first data to the second file system.

15. The storage medium of claim 11 , wherein the instructions when executed are to further cause the processor to:

implement a shim layer that is to intercept a data request sent to the first file system and communicate the data request to the second file system.

16. A computer system comprising:

a volatile memory to store a volatile page cache;

a persistent memory to store a persistent page cache; and

a processor configured to:

implement a first file system that is to send first data requests towards the volatile page cache;

implement a second file system that is to send second data requests towards the persistent page cache;

identify a request for first data from an application;

determine whether the persistent page cache stores a copy of the first data, wherein the persistent page cache is directly addressable by the processor and is to cache second data of a storage device that is not directly addressable by the processor; and

access the first data from the persistent page cache.

17. The computer system of claim 16 , wherein the processor is to:

identify a request for third data from a second application;

determine whether the volatile page cache stores a copy of the third data, wherein the volatile page cache is directly addressable by the processor and is to cache fourth data of the storage device; and

access the third data from the volatile page cache.

18. The computer system of claim 16 , wherein the volatile page cache is to be stored in a volatile memory that is further to store application code and application data.

19. The computer system of claim 16 , further comprising the storage device.

20. The computer system of claim 16 , further comprising one or more of: a battery communicatively coupled to the processor, a display communicatively coupled to the processor, or a network interface communicatively coupled to the processor.