Inventions

This is a list of patented or patentable inventions by Kasper Verdich Lund.

Lazy type tagging

Method and apparatus for facilitating lazy type tagging for compiled activations

United States Patent No. 7,181,732 invented by Lars Bak and Kasper Verdich Lund (February 20, 2007).

One embodiment of the present invention provides a system for type tagging values in a compiled activation frame in a lazy manner to facilitate garbage collection. This system operates in a mixed-mode environment that supports both interpretation of byte codes and execution of compiled native code. Upon receiving an invocation of a method, the system creates an activation frame for the method on the execution stack. If the method is executing in interpreted mode, the interpreter maintains a tag for each value in the activation frame during execution. The tag indicates whether the value is a reference type or a primitive type. However, if the method is executing in compiled mode, the system allocates space for tags for each value in the activation frame, but does not fill in the tags during execution. This allows the tags to be filled in at a future time when needed.

Removing unused compiled code

Non-intrusive gathering of code usage information to facilitate removing unused compiled code

United States Patent No. 6,738,969 invented by Lars Bak, Jakob Roland Andersen, and Kasper Verdich Lund (May 18, 2004).

One embodiment of the present invention provides a system that gathers code usage information to facilitate removing compiled code that has not been recently used. This method operates in a mixed-mode system that supports execution of both compiled code and interpreter code. During operation, the system gathers usage information for compiled methods within an application while the application is executing. Next, the system identifies compiled methods to be removed based on this usage information, and removes identified compiled methods so that interpreter code is executed for the compiled methods instead of compiled code. In this way, the system frees up the memory space used to store the compiled methods.

Inline cache sharing

Process and apparatus for sharing inline caches

United States patent application #20060242654 invented by Kasper Verdich Lund, Lars Bak, Jakob Roland Andersen, and Steffen Grarup (April 22, 2005).

A technique for dynamic dispatch involves adapting a method at a dispatch point to reference a state cache. State of the state cache may be associated with an object type and a method signature. When a method is adapted at the dispatch point to reference a state cache, the reference is to a state cache associated with a state that matches the method signature and the object type of the object dispatched upon. The state cache may be shared among multiple methods with similar associated states to reduce memory requirements.

Real-time relocation of objects

Process and system for real-time relocation of objects during garbage collection

United States patent application #20060248130 invented by Steffen Grarup, Lars Bak, Kasper Verdich Lund, and Jakob Roland Andersen (April 22, 2005).

A technique for dynamically relocating an object during garbage collection involves guaranteeing bounds on thread pause times. A process according to the technique may include pausing threads, bounding pause times by scanning only one of a plurality of threads, and resuming the threads. Another process according to the technique may include suspending a plurality of threads, relocating an object to a new memory location, updating references associated with an old memory location for only one of the threads such that the references are associated with the new memory location, and resuming the threads. In an embodiment, the process may include initially marking each of the threads "unscanned." In another embodiment, the process may include reading the object from the first memory location and writing the object to the second memory location. An example system according to the technique may include a scheduler and a relocation engine. In an embodiment, the scheduler may suspend threads in preparation for dynamic object relocation and then resumes the threads after scanning one, and only one, of the thread stacks. In an embodiment, the thread associated with the scanned thread stack may then be marked "scanned."

Code fragment sharing

Process and system for sharing program fragments

United States patent application #20060242631 invented by Jakob Roland Andersen, Lars Bak, Kasper Verdich Lund, and Steffen Grarup (April 22, 2005).

A technique for sharing code fragments involves detecting identical code fragments, then replacing code fragments with references to an identical code fragment. A process according to the technique may include detecting identical code fragments in one or more modules, presenting at runtime a single code fragment that is identical to the identical code fragments, and automatically sharing the single code fragment among the one or more modules. A system according to the technique may include a code fragments database that may includes code fragments and a code server configured to receive requests for a program and provide references to one or more of the code fragments in the code fragments database. Another system according to the technique may include a first object, a second object, and a method object, wherein a reference associated with a first method of the first object and the reference associated with a second method of the second object are pointers to the method object.


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