电脑内存最新优化与维护技巧及常见问题排解

采用哪些方法提高内存的使用效率和优化内存管理 （1）改变页面文件的位置 这样做其目的主要是为了保持虚拟内存的连续性。因为硬盘读取数据是靠磁头在磁性物质上读取,页面文件放在磁盘上的不同区域,磁头就要跳来跳去,自然不利于提高效率。而且系统盘文件众多,虚拟内存肯定不连续,因此要将其放到其他盘上。改变页面文件位置的方法操作如下：     

主流微型计算机硬件系统维护常见问题解答

怎样通过优化Windows的虚拟内存（页面文件）来提高物理内存的使用效能 虚拟内存实际上是物理内存不足时临时存放数据所使用的一部分硬盘空间,这样就扩大了计算机的可用内存空间以满足大型程序的运行要求。对于Windows 9X／Me而言,它所创建的虚拟内存就是Windows目录下的“Win386．swp”交换文件;而Windows2000／XP的虚拟内存则是根目录下的“Pagefile．sys”页面文件,两者的作用大致一样。     

LRU算法在改善虚拟内存性能方面的应用

移动学习已经成为一种趋势,然而大软件、大教学视频更加凸显手机系统内存的渺小。随着虚拟内存软件的开发,在某种程度上小内存也可以运行大程序。文章介绍手机存储的发展,分析两种增加虚拟内存的软件,针对虚拟内存软件存在的不足,通过对比3种页面置换算法,提出改善虚拟内存性能的一种LRU(Least Recently Used)改进算法。改进后的LRU算法降低缺页率,提高虚拟内存的使用效率,运行大型应用软件或播放大容量教学视频时更加流畅,响应时间更短。     

教你正确在Windows 7中设置虚拟内存

内存在计算机中的作用很大,电脑中所有运行的程序都需要经过内存来执行,如果执行的程序很大或很多,就会导致内存消耗殆尽.为了解决这个问题,WINDOWS运用了虚拟内存技术,即拿出一部分硬盘空间来充当内存使用,这部分空间即称为虚拟内存,虚拟内存在硬盘上的存在形式就是PAGEFILE.SYS这个页面文件.     

WINDOWS95性能的优化方法

Windows95是一种高性能的操作系统，是旧版本的DOS和Windows3．五所无法比拟的。但要用好Windows95是一个长期积累的过程。下面谈谈优化Windows95的一些途径，以期更好地使用它。1优化虚拟内存任何计算机系统由于条件限制，安装的RAM空间总是有限的、为此，Windows95在运行时总是要借助剩余的硬盘空间作为RAM空间的延伸（虚拟内存），以满足各种应用程序对内存的要求。所以在WISd0WS95的工作盘上应有足够的自由空间，否则在运行某些大型程序时，操作系统会报出内存不够的信息。1．1虚拟内存的概念Windows95安装成功后，会自动在硬盘…     

LRU页面置换算法的改进与实现

为简化嵌入式虚拟内存的实现,改善嵌入式虚拟内存的性能,在对常见页面置换算法进行对比分析的基础上,提出一种改进的最久未使用页面置换算法。该算法基于内存管理单元、跨页访问计数器、访问次序寄存器、溢出中断处理等软硬件相结合的技术。实验结果表明,该算法能提高嵌入式系统的页面置换效率,提升系统的整体性能,可广泛应用于各种物联网系统和嵌入式系统。     

经验点滴

硬盘分区要FAT32还是要NTFS?（续） 【硬盘剩余空间太少或碎片太多】 如果硬盘的剩余空间太少,由于一些应用程序运行需要大量的内存、这样就需要虚拟内存,而虚拟内存则是由硬盘提供的,因此硬盘要有足够的剩余空间以满足虚拟内存的需求。同时用户还要养成定期整理硬盘、清除硬盘中垃圾文件的良好习惯。     

电脑内存最新优化与维护技巧及常见问题排解

做好内存的优化与维护应掌握和了解哪些有关内存的基本常识 （1）物理内存和虚拟内存的含义 物理内存就是我们所能见到的内存条。而虚拟内存就是“假”的内存条，它是在硬盘上开辟的一个用于存储的空间，对于物理内存来说，它是一种扩展和补充。当内存空间紧张时，系统就会将一些暂时用不到的数据转存到虚拟内存当中。这就像在一个流动仓库中，管理员把一些滞销的货物先移到后备仓库去，将空间腾出来留给那些经常进出仓库的货物使用。     

嵌入式设备中的内存压缩机制

提出了一种适用于嵌入式设备的内存压缩机制。利用Linux的页面交换机制，创建一个基于内存的交换分区。当系统内存不足需要将某些页面交换到该分区上时，通过压缩这些页面向应用程序和用户提供更多的可用内存。使用空闲内存块匹配算法避免出现过多的内存碎片而影响系统性能。实验测试表明，使用该机制通常可以获得大于50%的可用内存。     

虚拟内存:你设对了吗?

当计算机的物理内存较小时,运行一些较大的程序内存就会不够用。操作系统会事先准备一部分硬盘空间,当内存不够用时,系统会自动将这部分硬盘空间用来当作内存使用,这部分内存就称为虚拟内存,通常也被称为页面文件或交换文件。虚拟内存通常以一个文件名的形式出现在硬盘分区中,在Windows 9X中文件名为Win386.swp,在Windows 2000、Windows XP中文件名为Pagefile.sys。     

Huge Page Friendly Virtualized Memory Management

With the rapid increase of memory consumption by applications running on cloud data centers,we need more efficient memory management in a virtualized environment.Exploiting huge pages becomes more critical for a virtual machine's performance when it runs large working set size programs.Programs with large working set sizes are more sensitive to memory allocation,which requires us to quickly adjust the virtual machine's memory to accommodate memory phase changes.It would be much more efficient if we could adjust virtual machines'memory at the granularity of huge pages.However,existing virtual machine memory reallocation techniques,such as ballooning,do not support huge pages.In addition,in order to drive effective memory reallocation,we need to predict the actual memory demand of a virtual machine.We find that traditional memory demand estimation methods designed for regular pages cannot be simply ported to a system adopting huge pages.How to adjust the memory of virtual machines timely and effectively according to the periodic change of memory demand is another challenge we face.This paper proposes a dynamic huge page based memory balancing system(HPMBS)for efficient memory management in a virtualized environment.We first rebuild the ballooning mechanism in order to dispatch memory in the granularity of huge pages.We then design and implement a huge page working set size estimation mechanism which can accurately estimate a virtual machine's memory demand in huge pages environments.Combining these two mechanisms,we finally use an algorithm based on dynamic programming to achieve dynamic memory balancing.Experiments show that our system saves memory and improves overall system performance with low overhead.     

Moving address translation closer to memory in distributed shared-memory multiprocessors

To support a global virtual memory space, an architecture must translate virtual addresses dynamically. In current processors, the translation is done in a TLB (translation lookaside buffer), before or in parallel with the first-level cache access. As processor technology improves at a rapid pace and the working sets of new applications grow insatiably, the latency and bandwidth demands on the TLB are difficult to meet, especially in multiprocessor systems, which run larger applications and are plagued by the TLB consistency problem. We describe and compare five options for virtual address translation in the context of distributed shared memory (DSM) multiprocessors, including CC-NUMAs (cache-coherent non-uniform memory access architectures) and COMAs (cache only memory access architectures). In CC-NUMAs, moving the TLB to shared memory is a bad idea because page placement, migration, and replication are all constrained by the virtual page address, which greatly affects processor node access locality. In the context of COMAs, the allocation of pages to processor nodes is not as critical because memory blocks can dynamically migrate and replicate freely among nodes. As the address translation is done deeper in the memory hierarchy, the frequency of translations drops because of the filtering effect. We also observe that the TLB is very effective when it is merged with the shared-memory, because of the sharing and prefetching effects and because there is no need to maintain TLB consistency. Even if the effectiveness of the TLB merged with the shared memory is very high, we also show that the TLB can be removed in a system with address translation done in memory because the frequency of translations is very low.     

对页面访问序列影响LRU页面置换算法的研究

页面置换算法是操作系统中虚拟存储管理的一个重要部分。改进页面置换算法,可以降低页面失败率,从而有效地提高系统性能。现有的应用于虚拟存储管理的页面置换算法主要是Least Reference Used(LRU)页面置换算法。文中利用页面访问间隔数,分析不同的页面访问序列对LRU算法的影响,把页面访问序列分为LRU-友好页面访问序列、LRU-不友好页面访问序列、不友好页面访问序列三类,为改进LRU页面置换算法提供了依据。     

面向虚拟机的远程磁盘缓存

在虚拟机(virtual machine)系统中,随着虚拟机数量和应用程序需求的不断增长,内存容量已经成为应用程序性能的主要瓶颈。为了提升内存密集型和I/O密集型程序的页面交换性能,提出了虚拟机的远程磁盘缓存机制REMOCA,它允许运行在一台物理主机上的虚拟机将其他物理主机的内存作为其二级磁盘缓存。由于网络传输延迟远远小于磁盘访问,用网络传输代替磁盘访问就能够有效地降低虚拟机的平均磁盘访问延迟。REMOCA的目标就要尽可能地减少磁盘访问。REMOCA运行在虚拟机管理器中,其基本工作原理是截获并处理虚拟机的页面淘汰、磁盘访问等事件。REMOCA能够与现有的虚拟机内存管理机制(如气球技术、影子缓存)相结合,从而提供更加灵活的内存资源管理策略。实验数据表明,REMOCA能有效地降低页面抖动对虚拟机性能的影响,并在很大程度上提升虚拟机中I/O密集型应用的性能。     

CC-NUMA系统中面向页迁移的反向页表技术

页迁移技术是实现CC-NUMA访存局部性优化的一种重要策略,其实现涉及到虚存系统中物理地址到虚拟地址的转换,传统做法需要遍历所有进程的虚拟地址空间,效率低、开销大.针对此问题,介绍了一种在操作系统内核中高效实现物理地址到虚拟地址转换的技术-一反向页表技术,并着重阐述了反向页表在页迁移策略中的应用.     

Segmentation,paging and optimal page sizes in virtual memory

On the basis of empirical data two topics concerning virtual memory systems are discussed: determining an optimal page size and performance of segmentation as compared to paging. Several production programs have been executed (on a simulator) both in a segmented system and in a paged system with various page sizes; the memory management was based on the working set policy. The memory usage and the fault rates were recorded, and the lifetime functions and space-time integrals were evaluated. The observations are explained using a new model of program behaviour which is a refinement of the phase-transition model. The results show that there is no globally optimal page size. Two characteristic types of programs are observed: the first requires a small page size and a large window size, the second requires a large page size and a small window size. Segmentation and paging are compared with respect to their usage of various resources. In the sense of the space-time integral, segmentation usually outperforms paging; if the mean segment size is large, the difference is remarkable. Several commonly used assumptions about the effects of page size on program behaviour are validated; some of them are found inaccurate or even wrong.     

An implementation of storage management in capability environments

The exploitation of the salient features of capability-based addressing environments leads to a high number of small objects existing in memory at the same time. It is thus necessary to enhance the efficiency of the mechanisms for object relocation, and to avoid congestion of input/output devices due to swapping. In this paper, we present an approach to the management of a large virtual memory space aimed at solving these problems. We insert partial information concerning the physical allocation of each object into the virtual identifier of this object. Objects are grouped into large swapping units, called pages. The page size is independent of the average object size. This results in enhanced efficiency in managing the relocation information both with regard to memory requirements and access times. The allocation of objects into pages, and the movement of pages through the memory hierarchy, are controlled by user processes. This means that programs which have knowledge of their own use of virtual memory can increase their locality of reference, diminish the number of swap operations and reduce fragmentation.     

Lightweight dynamic partitioning for last-level cache of multicore processor on real system

With rapid development of multi/many-core processors, contention in shared cache becomes more and more serious that restricts performance improvement of parallel programs. Recent researches have employed page coloring mechanism to realize cache partitioning on real system and to reduce contentions in shared cache. However, page coloring-based cache partitioning has some side effects, one is page coloring restricts memory space that an application can allocate, from which may lead to memory pressure, another is changing cache partition dynamically needs massive page copying which will incur large overhead. To make page coloring-based cache partition more practical, this paper proposes a malloc allocator-based dynamic cache partitioning mechanism with page coloring. Memory allocated by our malloc allocator can be dynamically partitioned among different applications according to partitioning policy. Only coloring the dynamically allocated pages can remit memory pressure and reduce page copying overhead led by re-coloring compared to all-page coloring. To further alleviate the overhead, we introduce minimum distance page copying strategy and lazy flush strategy. We conduct experiments on real system to evaluate these strategies and results show that they work well for reducing cache misses and re-coloring overhead.     

Program Behavior and the Page-Fault-Frequency Replacement Algorithm

Virtual memory is one of the major concepts that has evolved in computer architecture over the last decade. It has had a great impact on the design of new computer systems since it was first introduced by the designers of the Atlas computer in 1962. A virtual memory is usually divided into blocks of contiguous locations to allow an efficient mapping of the logical addresses into the physical address space. In this paper, we are concerned with paging systems, that is, systems for which the blocks of contiguous locations are of equal size. The memory system consists of two levels: main memory and auxiliary memory. The occurrence of a reference to a page that is currently not in main memory is called a page fault. A page fault results in the interruption of the program and the transfer of the referenced page from auxiliary to main memory.