file system cache

Link Address:http://www.jydba.net/aix-filesystemcache%e5%bc%95%e5%8f%91%e7%9a%84oracle%e4%ba%8b%e6%95%85/AIX uses the free physical memory as a file system cache to improve the system IO capability, and the default parameter can use 90% of physical

EXT3 IntroductionFor the ext3 file system, disk space divides a series of block groups, each of which has bitmaps to track the allocation and scope of inode and data blocks. Its physical layout is as follows:superblock: Located in Group No. 0 block,

Because recently to do a data study, need to put the data into storage, open source database, students may generally choose MySQL, but some of the MySQL functions can be too tired, so I replaced with Oracle more similar to the PostgreSQL, recently

ZH cheese: Ubuntu 14.04 installation lamp (linux,apache,mysql,php) has been introduced before lamp installation, this article mainly explain the lamp configuration.1. Configure Apache(1) Adjust the KeepAlive settings (refer to [1], [2]):On a server

In the previous blog in succession to record the query efficiency of the article. Today in the collation, write some of their own notes are as follows:Common reasons for slow queries are as follows:1. No index or index is not used.PS: Indexes are

IoScheduling PolicyIO scheduling strategy generally has btrfs Cfq,noop, Deadline three kinds ofAppendix:The overall goal of the IO Scheduler is to keep the head moving in one Direction , moving to the opposite direction , which is exactly the

Vmstat command Function descriptionThe Vmstat command can display the CPU usage, memory usage, and virtual memory exchange of the server including the IO read and write situation. Use the following: Vmstat [Options] [delay

Load AverageTransferred from: http://www.blogjava.net/sliverfancy/archive/2013/04/17/397947.html1.1: What is load? What is load Average?Load is the measure of how much the computer works (wikipedia:the system load is a measure of the amount of work,

The free command provides a more concise view of system memory usage relative to top:$ freeTotal used free shared buffers Cachedmem:255268 238332 16936 0 85540 126384-/+ buffers/cache:26408 228860swap:265000 0 265000some of the relevant notes:Mem:

Explanation of the content of Vmstat resultsVmstatprocs-----------Memory-------------Swap-------io------System-------CPU------R b swpd free buff cache si so bi bo in CS us sy ID WA St2 0 88 199564 134860 1175252 0 0 0 352 9323 10496 8 6 85 0

Kernel-related parametersRelevant kernel parameters, if conditions can be modified parameter test validation.1,/proc/sys/vm/dirty_ratioThis parameter specifies how much of the file system caches dirty pages (such as 10%), and the system has to start

The free command provides a more concise view of system memory usage relative to top: $ free Total used free shared buffers Cached mem:255268 238332 16936 0 85540 126384 -/+ buffers/cache:26408 228860 swap:265000 0 265000 Mem: represents

I believe we usually do Android applications, how much will be contacted to load pictures asynchronously, or load a large number of pictures of the problem, and load pictures we often encounter many problems, such as the image of the disorder, oom

Method Description: Open the file in an asynchronous fashion. In a POSIX system, path is assumed to exist by default (even if the files under that path do not exist) The flag identity may or may not be running under the network file system.

caching mechanisms in LinuxIn the Linux system, in order to improve the file system performance, the kernel uses a portion of physical memory to allocate buffers, for caching system operations and data files, when the kernel receives read and write

HTTP protocol Summary: Hyper text Transfer Protocol (Hypertext Transfer Protocol) is an abbreviation for transferring hypertext to a local browser from the World Wide Web (www:world Wide Web) server. The HTTP protocol belongs to the

1. Elasticsearch 2.0 Change 1.1 queries combined with filters Queries (Queries) and filters (filters) are merged-all filter clauses are now query clauses (ALL filter clauses are today query clauses.). Instead, the query clause can now be used in

What is InnoDB BUFFER POOL Computers use most of their memory to improve the performance of frequently accessed data. This is what we know about caching, which is a very important part of the system because accessing the hard disk can be as slow as

Recorded Top Column meaning Vmstat Procs Memory Swap Io System Cpu Uptime Free Iostat Cpu Device Sar Mpstat Pmap Netstat Tcpdump Strace Lsof Proc File system Benchmark Before Linux performance tuning, first need to understand the current service

explanation of Vmstat result content Vmstat procs-----------Memory----------      ---swap--  ----- IO----      --system--  -----CPU------          r b   swpd   free    buff       cache   si   so      bi    bo          in   cs          US sy ID WA