48 results about "Software cache" patented technology

A method to efficiently pre-fetch and batch compiler-assisted software cache accesses is provided. The method reduces the overhead associated with software cache directory accesses. With the method, the local memory address of the cache line that stores the pre-fetched data is itself cached, such as in a register or well known location in local memory, so that a later data access does not need to perform address translation and software cache operations and can instead access the data directly from the software cache using the cached local memory address. This saves processor cycles that would otherwise be required to perform the address translation a second time when the data is to be used. Moreover, the system and method directly enable software cache accesses to be effectively decoupled from address translation in order to increase the overlap between computation and communication.

A highly predictable, low overhead and yet dynamic, memory allocation methodology for embedded systems with scratch-pad memory is presented. The dynamic memory allocation methodology for global and stack data (i) accounts for changing program requirements at runtime; (ii) has no software-caching tags; (iii) requires no run-time checks; (iv) has extremely low overheads; and (v) yields 100% predictable memory access times. The methodology provides that for data that is about to be accessed frequently is copied into the SRAM using compiler-inserted code at fixed and infrequent points in the program. Earlier data is evicted if necessary.

The present invention provides for a method for computer program code optimization for a software managed cache in either a uni-processor or a multi-processor system. A single source file comprising a plurality of array references is received. The plurality of array references is analyzed to identify predictable accesses. The plurality of array references is analyzed to identify secondary predictable accesses. One or more of the plurality of array references is aggregated based on identified predictable accesses and identified secondary predictable accesses to generate aggregated references. The single source file is restructured based on the aggregated references to generate restructured code. Prefetch code is inserted in the restructured code based on the aggregated references. Software cache update code is inserted in the restructured code based on the aggregated references. Explicit cache lookup code is inserted for the remaining unpredictable accesses. Calls to a miss handler for misses in the explicit cache lookup code are inserted. A miss handler is included in the generated code for the program. In the miss handler, a line to evict is chosen based on recent usage and predictability. In the miss handler, appropriate DMA commands are issued for the evicted line and the missing line.

A compiler implemented software cache apparatus and method in which non-aliased explicitly fetched data are excluded are provided. With the mechanisms of the illustrative embodiments, a compiler uses a forward data flow analysis to prove that there is no alias between the cached data and explicitly fetched data. Explicitly fetched data that has no alias in the cached data are excluded from the software cache. Explicitly fetched data that has aliases in the cached data are allowed to be stored in the software cache. In this way, there is no runtime overhead to maintain the correctness of the two copies of data. Moreover, the number of lines of the software cache that must be protected from eviction is decreased. This leads to a decrease in the amount of computation cycles required by the cache miss handler when evicting cache lines during cache miss handling.

Mechanisms for performing useful computations during a software cache reload operation are provided. With the illustrative embodiments, in order to perform software caching, a compiler takes original source code, and while compiling the source code, inserts explicit cache lookup instructions into appropriate portions of the source code where cacheable variables are referenced. In addition, the compiler inserts a cache miss handler routine that is used to branch execution of the code to a cache miss handler if the cache lookup instructions result in a cache miss. The cache miss handler, prior to performing a wait operation for waiting for the data to be retrieved from the backing store, branches execution to an independent subroutine identified by a compiler. The independent subroutine is executed while the data is being retrieved from the backing store such that useful work is performed.

The use of heap memory is optimized by extending a cache implementation with a CacheInterface base class. An instance of a ReferenceToCache is attached to the CacheInterface base class. The cache implementation is registered to a garbage collector application. The registration is stored as a reference list in a memory. In response to an unsatisfied cache allocation request, a garbage collection cycle is triggered to check heap occupancy. In response to exceeding a threshold value, the reference list is traversed for caches to be cleaned based upon a defined space constraint value. The caches are cleaned in accordance with the defined space constraint value.