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.

Accelerating Relational Databases by Leveraging Remote Memory and RDMA

Abstract: Memory is a crucial resource in relational databases (RDBMSs). When there is insufficient memory, RDBMSs are forced to use slower media such as SSDs or HDDs, which can significantly degrade workload performance. Cloud database services are deployed in data centers where network adapters supporting remote direct memory access (RDMA) at low latency and high bandwidth are becoming prevalent. We study the novel problem of how a Symmetric Multi-Processing (SMP) RDBMS, whose memory demands exceed locally-available memory, can leverage available remote memory in the cluster accessed via RDMA to improve query performance. We expose available memory on remote servers using a lightweight file API that allows an SMP RDBMS to leverage the benefits of remote memory with modest changes. We identify and implement several novel scenarios to demonstrate these benefits, and address design challenges that are crucial for efficient implementation. We implemented the scenarios in Microsoft SQL Server engine and present the first end-to-end study to demonstrate benefits of remote memory for a variety of micro-benchmarks and industry-standard benchmarks. Compared to using disks when memory is insufficient, we improve the throughput and latency of queries with short reads and writes by 3X to 10X, while improving the latency of multiple TPC-H and TPC-DS queries by 2X to 100X.

Resource usage analysis

Abstract: It is an important criterion of program correctness that a program accesses resources in a valid manner. For example, a memory region that has been allocated should eventually be deallocated, and after the deallocation, the region should no longer be accessed. A file that has been opened should be eventually closed. So far, most of the methods to analyze this kind of property have been proposed in rather specific contexts (like studies of memory management and verification of usage of lock primitives), and it was not clear what the essence of those methods was or how methods proposed for individual problems are related. To remedy this situation, we formalize a general problem of analyzing resource usage as a resource usage analysis problem, and propose a type-based method as a solution to the problem.

Controlling memory usage in systems having limited physical memory

Abstract: Described herein is a method of controlling memory usage in a computer system having limited physical memory, wherein one or more application programs execute in conjunction with an operating system. At a first memory usage threshold, the operating system requests at least one of the application programs to limit its use of memory. At a second memory usage threshold that is more critical than the first memory usage threshold, the operating system requests at least one of the application programs to close itself. At a third memory usage threshold that is more critical than the first and second memory usage thresholds, the operating system terminates at least one of the application programs without allowing its further execution.

Memory space management method, data transfer method, and computer device for distributed computer system

Abstract: A scheme for realizing a high speed data transfer between memory spaces shared among computers in a distributed computer system, without requiring a complicated and inefficient communication protocol processing at the computer side One region which is at least a part of a virtual memory space or a real memory space managed by one computer and another region which is at least a part of a virtual memory space or a real memory space managed by another computer are shared between these two computers, and a dedicated virtual connection is set up between these two shared regions Then, a data transfer between these two shared regions is carried out by using the dedicated virtual connection A virtual connection identifier of the dedicated virtual connection is registered into a corresponding page table entry in the page table, so that this virtual connection identifier can be obtained at a time of the data transfer by referring to the page table alone

Implementation and evaluation of shared-memory communication and synchronization operations in MPICH2 using the Nemesis communication subsystem

Abstract: This paper presents the implementation of MPICH2 over the Nemesis communication subsystem and the evaluation of its shared-memory performance. We describe design issues as well as some of the optimization techniques we employed. We conducted a performance evaluation over shared memory using microbenchmarks. The evaluation shows that MPICH2 Nemesis has very low communication overhead, making it suitable for smaller-grained applications.