US 7,065,763 B1 · Method of reducing contention of a highly contended lock protecting multiple data items

Abstract

Featured is a method or process for reducing contention of a highly contended software lock(s) that is protecting multiple data items, where the software has a plurality of code paths accessing the data items. The method includes creating additional partition locks to protect subsets of the data items protected by the existing global lock. Such a method further includes acquiring all partition locks and the global lock, wherever a global lock would have been acquired to protect data. The method also includes identifying one or more heavily used code paths and determining which data items are touched by the identified one or more heavily used code paths. These data items are then moved into a partition, if they were not partitioned earlier. The locking requirements for each of the identified one or more heavily used code paths are optimized to match the reduced locking requirements because of the partitioned data items. In other words the locking requirements are reduced so only the locks for the partitions including the data items that touch the code path are acquired. In more specific embodiments, the so-modified software is evaluated to determine if there is an acceptable increase in overall system performance resulting from the optimization of the locking requirements. If the modified system's performance is not acceptable, then the next most heavily used code path is identified and the locking requirements for this code path are optimized. Such optimization is continued until the system exhibits an acceptable overall system performance or all code paths are optimized.

Claims22

Dependent claims

A method for reducing contention of a highly contended software lock protecting data items of a data set, all of the data items being stored in a system memory of a multi-processor computer system, said method comprising the steps of:

defining partitions within the data set;
creating N partition locks, one for each partition, where N>2;
identifying one code path from one or more code paths of a software program that access one or more of the data items;
determining which data items of the data set are accessible by the identified code path;
partitioning at least a portion of the data items that are accessible by the identified code path into the partitions;
and
optimizing locking requirements of the identified code path so the locks being acquired and released in the identified code path are those associated with the data items being accessible by the identified code path, wherein the identified code path includes a plurality of branches, and wherein said optimizing includes optimizing the locking requirements of the identified code path so the locks being acquired and released in the code path are those associated with the data items being accessible by each branch of identified code path.

4 more elements

first determining a methodology for partitioning the data set into partitions;
creating N partition locks, one for each partition, where N>2;
modifying locking requirements of each of one or more code paths of a software program that access one or more of the data items so as to acquire all N partition locks and a global lock where the global lock would have been acquired prior to accessing of the one or more data items and so as to release all N partition locks and the global lock where the global lock would have been released after accessing of the one or more data items;
identifying one code path from the one or more code paths of the software program that access one or more of the data items, wherein the code path first identified is the heaviest used code path and wherein the another code path and subsequent code paths are identified sequentially in the direction from the heaviest used code path to a lesser used path;
next determining which data items of the data set are accessible by the identified code path;
partitioning at least one of the data items that are accessible by the identified code path;
and
optimizing the locking requirements of the identified code path so the locks being acquired and released in the identified code path are those associated with the data items being accessible by the identified code path;
evaluating the software program after said optimizing the locking requirements so as to determine if overall performance of the software program is acceptable, wherein the overall system performance is based on reducing contention of the highly contended software lock;
and
in the case where said evaluating determines that the overall performance of the software program is not acceptable, then identifying another code path of the one or more code paths and repeating said steps of determining, partitioning, optimizing and evaluating for the another identified code path.

8 more elements

A method for accessing one or more data items in a data set by a software program, all of the data items being stored in a system memory of a multi-processor computer system, said method comprising the steps of:

defining partitions within the data set;
creating N partition locks, one for each partition, where N>2;
identifying one code path from one or more code paths of the software program that access one or more of the data items;
determining which data items of the data set are touched by the identified code path;
partitioning at least one of the data items that are accessible by the identified code path;
optimizing locking requirements of the identified code path so the locks being acquired and released in the identified code path are those associated with the data items being accessible by the identified code path;
locking the data items of the data set that are touched by the identified code path while keeping unlocked the data items of the data set that are not being accessible by the identified code path;
accessing one or more of the locked data items;
modifying the locking requirements of the one or more code paths of the software program that access one or more of the data items so as to acquire all N partition locks and a global lock where the global lock would have been acquired prior to accessing of the one or more data items and so as to release all N partition locks and the global lock where a global lock would have been released after accessing of the one or more data items;
and
releasing the locks associated with the locked data.

8 more elements

Dependencies are inferred from the claim text.

Method of reducing contention of a highly contended lock protecting multiple data items

Life of this patent

Method of reducing contention of a highly contended lock protecting multiple data items

Life of this patent

Abstract

Claims22