scratchpad io

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 elevator model in real life , so the IO Scheduler is also called an elevator. . (elevator) and the corresponding algorithm is called elevator algorithm . and There are

Java.io operation is the basis of the Java Foundation, if no IO operation program will not run, so, and review the contents of the java.io operation, the object serialization is the basis of the Java EE, is the implementation of distributed deployment and call the foundation, there are a lot of file system, Read and write network resources, and so on.For the inside of the personal feel of the more important knowledge to do a figure summed up a bit. As

Thread IO ModelThe first thing to remember is that Redis is a single-threaded thread.Why is a single thread so fast?All Redis data is in memory, and all operations are memory-level operations, so the speed is faster than on-disk operations. But it is also because it is single-threaded, so be careful with the time-complexity O (n) instructions.How does a single thread handle so many concurrent client connections?Multiplexing.Non-blocking IOThe socket m

IntroductionMost of the IO statistics tools under Linux, such as Iostat, Nmon, and so on, are only counted to the Per Device's read and write situations, and if you want to know how each process uses IO, it's a bit cumbersome.Iotop is a top class tool used to monitor disk I/O usage. Iotop has a UI similar to top, which includes information about PID, user, I/O, process, and so on.ExampleJust run it straight

First, IntroductionA few days ago using a Linux memory Detection tool Valgrind, want to redirect the results of the detection to a file, the result is always no content, finally found that the reason for the redirect, it output the information is output to stderr, so I use > file This command is clearly not achieving its purpose.Second, learningSo decided to review the knowledge of IO redirection, and found the following article.IO redirectionUNIX ha

Reduce disk IO IO for distributed disks 1, the table space using local management, the file spread to different devices 1 separate the data file from the log file 2 Reduce server-independent disk IO 3 Evaluate the use of bare equipment 4) partition Table data 2, the use of table space System tablespace reserved for data dictionary objects Create a local

The Java API native supports IO operations. Java IO is primarily designed to read (input) and write (ouput) data.Most programs need to process some input data (such as file data, network data, and so on) and produce output based on these input data. Here are a few scenarios where we often encounter:1. The compression software needs to read the file to be compressed and output the compressed file to another