Cache region concept

• US 7,996,615 B2
• Filed: 07/07/2010
• Issued: 08/09/2011
• Est. Priority Date: 12/28/2004
• Status: Expired due to Fees

• Current Assignee: SAP SE
• Original Assignee: SAP AG (SAP SE)
• Inventors: Marwinski, Dirk, Kilian, Frank, Galchev, Galin, Luik, Oliver, Petev, Petio G.
• Primary Examiner(s): Shah; Sanjiv
• Assistant Examiner(s): Savla; Arpan P.
• Application Number:
  US12/831,918
• Publication Number:
  US 20100268881A1
• Time in Patent Office: 398 Days
• Field of Search: 711/119, 711/121, 711/130, 711133-135, 711/147, 711/157, 711/159, 707/813, 718/1
• US Class Current: 711/119
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 12/084 with a shared cache
• CPC Class Codes: G06F 12/0842 for multiprocessing or multitasking
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/121 using replacement algorithms
• CPC Class Codes: G06F 2212/1021 Hit rate improvement
• CPC Class Codes: G06F 2212/282 Partitioned cache
• CPC Class Codes: G06F 9/455 Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines

Abstract

A method to associate a storage policy with a cache region is disclosed. In this method, a cache region associated with an application is created. The application runs on virtual machines, and where a first virtual machine has a local memory cache that is private to the first virtual machine. The first virtual machine additionally has a shared memory cache that is shared by the first virtual machine and a second virtual machine. Additionally, the cache region is associated with a storage policy. Here, the storage policy specifies that a first copy of an object to be stored in the cache region is to be stored in the local memory cache and that a second copy of the object to be stored in the cache region is to be stored in the shared memory cache.

Claims

1. A method comprising:

creating a first cache region associated with an application, the first cache region being one of a plurality of cache regions associated with the application, each of the plurality of cache regions being associated with a different caching treatment policy, the application running on a plurality of virtual machines, a first one of the plurality of virtual machines having a local memory cache that is private to the first one of the plurality of virtual machines and a shared memory cache that is shared by the first one of the plurality of virtual machines and a second one of the plurality of virtual machines;

associating the first cache region with a first storage policy, the first storage policy specifying that a first copy of an object to be stored in the first cache region is to be stored in the local memory cache and that a second copy of the object to be stored in the first cache region is to be stored in the shared memory cache;

receiving a request from the application to retrieve the object, the object having been stored in the first cache region;

detecting that a second version of the object is newer than a first version of the object, the second version of the object being stored in the shared memory cache and the first version of the object being stored in the local memory cache; and

providing the second version of the object to the application,

wherein the providing of the second version of the object comprises copying the second version of the object from the shared memory cache to the local memory cache.

2. The method of claim 1, wherein the providing of the second version of the object further comprises enabling the application to establish a hard reference to the second version of the object in the local memory cache, an identifying of the hard reference by a garbage collector preventing the garbage collector from removing the second version of the object from the local memory cache.

3. The method of claim 1, wherein the first storage policy further specifies that an eviction of the object from the local memory cache is to result in a storage of the object in a storage resource having a higher latency than the local memory cache.

4. The method of claim 3, wherein the storage resource is a shared memory associated with the shared memory cache.

5. The method of claim 1, further comprising:

creating a second cache region associated with the application; and

associating the second cache region with a second storage policy, the second storage policy specifying that a first version of an additional object to be stored in the second cache region is to be stored in the shared memory cache and that the first version of the additional object is not to be modified.

6. The method of claim 5, further comprising:

receiving a request from the application to incorporate a modification into the additional object, the additional object having been stored in the second cache region; and

in response to the receiving of the request from the application to incorporate the modification, incorporating the modification into a second version of the additional object and storing the second version of the additional object in the shared memory cache.