Methods and systems for distributed caching in presence of updates and in accordance with holding times

• US 20050071569A1
• Filed: 11/23/2004
• Published: 03/31/2005
• Est. Priority Date: 03/07/2002
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Iyengar, Arun Kwangil, Rouvellou, Isabelle M.
• Granted Patent: US 7,673,108 B2
• Time in Patent Office: Days
• US Class Current: 711/133
• CPC Class Codes: G06F 12/0811 with multilevel cache hierarchies
• CPC Class Codes: G06F 12/121 using replacement algorithms
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching

Abstract

Techniques for improved cache management including cache replacement are provided. In one aspect, a distributed caching technique of the invention comprises the use of a central cache and one or more local caches. The central cache communicates with the one or more local caches and coordinates updates to the local caches, including cache replacement. The invention also provides techniques for adaptively determining holding times associated with data storage applications such as those involving caches.

Claims

1. A method of determining a time for an event to occur, comprising the steps of:

determining a threshold time value t1;

determining if a frequency of an event occurring is low;

in response to the frequency being low, causing the event to occur; and

in response to the event not occurring after t1 has elapsed, causing the event to occur.

2. The method of claim 1, wherein the step of determining if a frequency of an event is low further comprises determining if a time between successive events one of equals and exceeds a second threshold time value t0.

3. The method of claim 1, further comprising the step of locking a data object by a process wherein the event comprises unlocking the data object and successive events comprise accesses to the data object by the process.

4. The method of claim 3, further comprising the step of increasing t1 in response to the process accessing the data object at a high rate.

5. The method of claim 3, further comprising the step of decreasing t1 in response to frequent requests to lock the data object.

6. The method of claim 3, wherein the data object is locked by a cache.

7. The method of claim 2, further comprising the steps of:

locking a data object by a process in which the event comprises unlocking the data object and the successive events comprise updates to the data object by the process; and

decreasing t0 in response to frequent requests to lock the data object.

8. Apparatus for determining a time for an event to occur, the apparatus comprising:

at least one processor operative to;

(i) determine a threshold time value t1;

(ii) determine if a frequency of an event occurring is low;

(iii) in response to the frequency being low, cause the event to occur; and

(iv) in response to the event not occurring after t 1 has elapsed, cause the event to occur; and

memory, operatively coupled to the at least one processor, for storing at least a portion of results of one or more operations performed by the at least one processor.

9. An article of manufacture for determining a time for an event to occur, comprising a machine readable medium containing one or more programs which when executed implement the steps of:

determining a threshold time value t1;

determining if a frequency of an event occurring is low;

in response to the frequency being low, causing the event to occur; and

in response to the event not occurring after t1 has elapsed, causing the event to occur.