First, the real-time machine of Linux is analyzed. Then, based on the characteristics of multimedia applications, the embedded Linux System for multimedia applications is constructed by improving the real-time performance of Linux systems. Experimental results show that the
Timer and Time managementThe system timer is a programmable hardware chip that generates interrupts at a fixed frequency. This interrupt is called a timer interrupt, and its corresponding interrupt handler is responsible for updating the system time and performing tasks that need to be run periodically. The system timer and clock interrupt handlers are the backbone of the
Concurrent Linux under the high concurrency of Nginx server, when the number of TCP time_wait sockets often reach 20,000 or 30,000, the server can easily be dragged to death. By modifying the Linux kernel parameters, you can reduce the number of time_wait sockets on the Nginx server.Vi/etc/sysctl.confAdd the following lines:ReferenceNet.ipv4.tcp_fin_timeout = 30Net.ipv4.tcp_keepalive_time = 1200Net.ipv4.tcp
Original address: http://blog.csdn.net/imtgj/article/details/7107489? Reload
In view of the recent issues related to CPU usage that involve the scheduling algorithm of Linux kernel, it is necessary to understand. Therefore, I wrote this article. Common Linux tasks include real-time tasks and non-real-time tasks. The s
sequential order requirement. The keyId specified when the client executes the Ntpdate Synchronization command is consistent with the values in the key file. The values and strings recorded for each strip need to be provided to the client, which the client needs to authenticate to synchronize.7, modify the next time zone Cp/usr/share/zoneinfo/asia/hong_kong/etc/localtime I do not know whether to modify the time
) and hard real-time systems. Soft real-time systems are those systems that allow missed time limits (deadline) when the system is heavily loaded and do not cause too much harm, such as videoconferencing systems, while hard-time systems are those systems that require very strict scheduling times for each task, and if t
Modify the Linux kernel parameters to reduce the TIME-WAITsockets-Linux Enterprise Application-Linux server application information in the TCP connection. For more information, see the following. Since the launch of a new set of Apache servers, I used the netstat-an command to find a large number of TCP connections in
Linux ntp time server configuration tutorial, ntp server configuration
Network Time Protocol (NTP) is also a new test requirement for RHCE. During study, I also reviewed how to set the Linux Time. Now I will share it with you.
It is not difficult to set up the NTP server, b
A new solution to improve the real-time performance of Embedded Linux-general Linux technology-Linux programming and kernel information. The following is a detailed description. Author: Cui Ke, Graduate School of Chinese Emy of sciences, Chen Wei, China University of Science and Technology
Improving the real-
In windows, windows provides the task scheduling function. Today, we mainly learn how to use the at command for one-time scheduled tasks in linux.
In windows, windows provides the task scheduling function. in the control panel-> performance and maintenance-> task scheduling, the function is to schedule tasks that run automatically. You can create a scheduled task through step-by-step guidance of 'add Task S
message segment, Acknowledgment Number Sequence Number add 1; Host 1 into the FIN_WAIT_2 state; Host 2 tells the host 1, I also have no data to send, you can close the connection;Third breakup: Host 2 to the host 1 send a FIN message segment, request to close the connection, while the host 2 into the CLOSE_WAIT State;The fourth break: Host 1 received the host 2 sent the message segment, FIN to host 2 sent a ACK message segment, and then host 1 into the TIME_WAIT state, host 2 received a host 1
[Turn fromQing_gee's Column: http://blog.csdn.net/qing_gee/article/details/42234997]Preface : In our project, need to synchronize the time of the Linux server, so used the Ntpdate command, in the crontab is configured, set to every hour of the full-time minutes to synchronize, after the end has been no concern, because it is very simple, empiricism told me, Since
every time)Note: The Linux signal mechanism is basically inherited from UNIX systems. In early Unix systems, the signal mechanism was relatively simple and original, and some problems were exposed in practice. Therefore, the signals built on the early mechanism were called "unreliable signals ", signals smaller than sigrtmin (sigrtmin = 32, sigrtmax = 63) are unreliable signals. This is the source of "unre
Network time Protocol (NTP) is also a new exam requirement for RHCE. Study time also by the way to review how to set up Linux time, now take out and share with youSetting up an NTP server is not difficult, but NTP itself is a very complex protocol. Here's just a brief introduction to the practical approachLike last
How to Improve the Linux level in a short period of time-Linux general technology-Linux technology and application information. The following is a detailed description. The first thing I want to talk about is that I have already applied this method. At the suggestion of a Linux
Linux real-time monitoring tool vmstat
The official definition of vmstat is vmstat-Report virtual memory statistics, which is the statistics of virtual memory.
First, tracing:
What is virtual memory?
A: The virtual memory is a virtual file on the disk that can be used as the memory.
Why is there virtual memory?
A: The program needs to run through the memory. If the program consumes too much memory during ex
basically no problem. (PlainText password)
In the intranet environment words do not know the main station target can nslookup domain name to see whether in an intranet and so on.
Intranet environment If there is running FTP service to do backdoor record FTP password, collect information, wait for management on-line.
Use Tcpdump
Leave a hidden back door.
Get permission to do th
Article Title: linux tips -- set the clock and time. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
Introduction:
This document explains how to set a computer clock in
While (time_before (jiffies, J1 )){Schedule ();}
Running idle tasks (process number 0, also known as Swapper for historical reasons) when the computer is idle can reduce the workload of the processor, reduce the temperature, and increase the service life.
Timeout
The best way to implement latency is to let the kernel complete the corresponding work for us.
(1) if the driver uses a waiting queue to wait for some other events and wants to en
This document explains how to set a computer clock in Linux, how to set your time zone, and other materials related to how Linux saves time.
Your computer has two clocks. One is a always-running, battery (hardware, bios, or CMOS) clock, the other is the (system) Clock maintained by the operating system running on y
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