Memory management

About: Memory management is a research topic. Over the lifetime, 16743 publications have been published within this topic receiving 312028 citations. The topic is also known as: memory allocation.

Design tradeoffs for software-managed TLBs

Abstract: An increasing number of architectures provide virtual memory support through software-managed TLBs. However, software management can impose considerable penalties, which are highly dependent on the operating system's structure and its use of virtual memory. This work explores software-managed TLB design tradeoffs and their interaction with a range of operating systems including monolithic and microkernel designs. Through hardware monitoring and simulations, we explore TLB performance for benchmarks running on a MIPS R2000-based workstation running Ultrix, OSF/1, and three versions of mach 3.0.Results: New operating systems are changing the relative frequency of different types of TLB misses, some of which may not be efficiently handled by current architectures. For the same application binaries, total TLB service time varies by as much as an order of magnitude under different operating systems. Reducing the handling cost for kernel TLB misses reduces total TLB service time up to 40%. For TLBs between 32 and 128 slots, each doubling of the TLB size reduces total TLB service time up to 50%.

WCET-Directed Dynamic Scratchpad Memory Allocation of Data

Abstract: Many embedded systems feature processors coupled with a small and fast scratchpad memory. To the difference with caches, allocation of data to scratchpad memory must be handled by software. The major gain is to enhance the predictability of memory accesses latencies. A compile-time dynamic allocation approach enables eviction and placement of data to the scratchpad memory at runtime. Previous dynamic scratchpad memory allocation approaches aimed to reduce average-case program execution time or the energy consumption due to memory accesses. For real-time systems, worst-case execution time is the main metric to optimize. In this paper, we propose a WCET-directed algorithm to dynamically allocate static data and stack data of a program to scratchpad memory. The granularity of placement of memory transfers (e.g. on function, basic block boundaries) is discussed from the perspective of its computation complexity and the quality of allocation.

File system for non-volatile computer memory

Abstract: A memory management system for random access memories employs a novel B-tree structure to map physical memory locations to logical addresses. In the preferred arrangement each key in the tree structure contains the physical address corresponding to the logical address identifying the key and also contains the size of the data block at that address. The invention also provides a novel arrangement for updating B-trees in response to changes in the keys. The tree buckets containing modified keys are recorded in storage locations other than the locations containing the keys prior to modification. Thus, until the modification of the tree is complete, the system contains a record of the entire tree structure prior to the beginning of the modification.

Device memory management during electronic file updating

Abstract: In performing memory management, an upgrade client (130) of a host device identifies and reserves memory blocks large enough to accommodate new software components by performing sequential searches of first and second memory areas. The new software components are updated versions of components of original software files (110). When the new component size exceeds that of available blocks of the first and second memory areas, the upgrade client (130) rewrites the first memory area to eliminate unused memory blocks, reapportions the first and second memory areas, writes the new component to the second memory area, and updates a vector table. To access host device software components, the upgrade client receives a function call from the main program of the host device (104) including identification information of corresponding software files, reads a start address of the corresponding software files from the vector table, and generates a call for the corresponding software files.

An efficient management scheme for large-scale flash-memory storage systems

Abstract: Flash memory is among the top choices for storage media in ubiquitous computing. With a strong demand of high-capacity storage devices, the usages of flash memory quickly grow beyond their original designs. The very distinct characteristics of flash memory introduce serious challenges to engineers in resolving the quick degradation of system performance and the huge demand of main-memory space for flash-memory management when high-capacity flash memory is considered. Although some brute-force solutions could be taken, such as the enlarging of management granularity for flash memory, we showed that little advantage is received when system performance is considered. This paper proposes a flexible management scheme for large-scale flash-memory storage systems. The objective is to efficiently manage high-capacity flash-memory storage systems based on the behaviors of realistic access patterns. The proposed scheme could significantly reduce the main-memory usages without noticeable performance degradation.