linux job scheduler

Linux I/O scheduler algorithm introduction from: http://www.realzyy.com /? P = 984 Io sched is a method used by the operating system to determine the order of Io operations submitted on Block devices. There are two purposes: Improving Io throughput and reducing Io response time. However, Io throughput and IO response time are often in conflict. To balance the two as much as possible, the IO

Tags: timed view def program is Job/etc/shell absolute pathTask Scheduler: Backup data at specific times, restart services, shell scripts, individual commands, and more.Task Scheduler Profile: Cat/etc/crontab[Email protected] ~]# Cat/etc/crontabShell=/bin/bashPath=/sbin:/bin:/usr/sbin:/usr/binMailto=root# for details see Mans 4 Crontabs# Example of

; default management of their own;-l:list, list the tasks;-r:remove to remove all tasks;-e:edit, edit, open a default editor for the current shell session to edit the cron task table;Ctrl+d Submitting a taskExample: I write to/etc/crontab1, every Monday to Saturday 3:20 A.M., run the CP command to archive the/etc/directory, storage location is/BACKUPS/ETC-YYYY-MM-DD;3 * * 1-6 root/bin/cp-a/etc//backups/etc-' date +%f ' >/dev/null 2>12, every Sunday 2:30 A.M., run the CP command to backup the/etc

(950000US):Sysctl_sched_rt_runtime, see the explanation of the sysctl_sched_rt_period variable/proc/sys/kernel/sched_compat_yield (0):Sysctl_sched_compat_yield, this parameter allows the Sched_yield () system call to be more efficient, allowing it to use fewer CPUs, and for applications that rely on Sched_yield for better performance, consider setting it to 1/proc/sys/kernel/sched_migration_cost (500000ns):Sysctl_sched_migration_cost the variable is used to determine if a process is still hot,

Linux Task Scheduler:Disposable execution:At,batchBatch: Does not need to specify a time and will be executed during idle timePeriodic execution:Vixie Cron:crontabWhat we usually see is that crontab,crontab is actually a form or file that provides configuration information for a process Crond Vixie cron.1, one-time task execution:At timeAt>CTRL+D: Submitting a taskAt-l = atq: View tasks waiting to be performedAt 11:30Noon,midnight,teatimeCases:[[Email

I. Description of CRONTABLinux crontab task scheduling is to perform the corresponding tasks within the specified time frequency.Ii. details of crontab documents1. crontab files in Linux/etc/crontab2. View crontab File # Vi/etc/crontab file description belowShell=/bin/bashPath=/sbin:/bin:/usr/sbin:/usr/binMailto=roothome=/# for details see Mans 4 Crontabs# Example of Job definition:#.----------------Minute

http://www.ibm.com/developerworks/cn/linux/l-linux-scheduler-simulator/LinschedLinsched is a Linux scheduler emulator that resides in user space. It isolates the Linux scheduler subsyst

, weighted minimum connection; (Default algorithm)Overhead= (activeconnections*256+inactiveconnections)/weightNote: The first time the dispatch, according to the order configured in Ipvsadm the top-down distribution; The weights do not play a role in the first time dispatch;Sed:shortest expection delay, shortest expected delay;Overhead= (activeconnections+1) *256/weightNote: SED can solve the problem of beginning injustice, but the weight gap is relatively large, it may lead to unfairness;Nq:nev

Linux operating system The minimum granularity of the timing scheduler can only be adjusted to the minute level, work sometimes need to be in the second schedule, so you need to write scripts to implement#!/bin/bashwhile [true]; Do/bin/sleep #在这里能够编写自己复杂的业务代码netstat-N | grep 8020 >>/root/data/flume.logecho 10.58...### ' Date ' >>/root/data/flume.logdoneAfter writing, submit the script (mycrontab.sh) to the

10.23 Linux Task Scheduler cronThe crontab command is used to submit and manage the tasks that the user needs to perform periodically, similar to the Scheduled tasks under Windows, when the operating system is installed, the Service tool is installed by default and the Crond process is started automatically. The Crond process periodically checks to see if there is a task to perform and automatically execute

Task Schedule:1. Perform a task at a future point in time:#at#at [OPTION] TimeAt>commandAt>, .....At>ctrl+d Submit[OPTION]-L Displays the job list, equivalent to the #atq commandThe display format is as follows:JOBID RUNTIME ALIGNMENT USERALIGNMENT (queues) can only be represented by a single character, and the default queue is listed as a.-D JOBID Delete job, equivalent to the #atrm command.TimeAbsolute ti

Linux Task Scheduler Cron[Email protected] ~]# CRONTAB-ENo crontab for root-using an empty oneThis is done 3 o'clock in the morning every day.0 3 * * */usr/bin/touch/root/123.txt >/dev/nullStart the service[Email protected] ~]# systemctl start CrondBasic format:* * * * * commandTime-sharing Weekly commandThe 1th column represents minutes 1~59 per minute with * or */1The 2nd column represents the hour 1~23 (

I. Linux Task Scheduler cronThe operation of the Cron Task Scheduler function is done through the crontab command.Among the options that are commonly used are:-U: Specify a user, the no-u option is the current user;/etc/crontab a configuration file for a task planThe first two lines are defined variables, the third line refers to who sent the message, and then th

Tags: field status str stop kind level handy device pngOne, the Linux system's task planThe crontab command is used to submit and manage the tasks that the user needs to perform periodically, similar to scheduled tasks under Windows, when the operating system is installed, the Service tool is installed by default, and the Crond process is started automatically, and the Crond process periodically checks for the tasks to be performed every minute. If th

details see Mans 4 Crontabs# Example of Job definition:#.----------------Minute (0-59)# | .-------------Hour (0-23)# | | .----------Day of Month (1-31)# | | | .-------month (1-12) OR jan,feb,mar,apr ...# | | | | .----Day of Week (0-6) (sunday=0 or 7) or Sun,mon,tue,wed,thu,fri,sat# | | | | |# * * * * * * user-name command to be executedB, user cron: usually defined in/var/spool/cron/username.To implement user cron using the crontab command:-L: View y

types of work scheduling for Linux At: handles the command to end the transfer only once, and requires the support of the ATD service when executing the AT command. Crontab: The set of work cycles is performed continuously, with a cycle time of minutes, hours, weekly, monthly, and yearly. at: First find/etc/at.allow This file, the user written in this file can use at, Users who are not written in this file will not be abl

There is a mail service function inside the Linux system/var/spool/mailCentOS6, 7 The default is to open the mail service-s Specifies the subject of the message-A file_name adding attachments-R Specify the message source-U Specify the purpose of the messageHello World is the subject of the message this message is sent to root. EoT above, that is, on behalf of the message content input completed.Mail is querying your own message 1 means you need to see

Tags: Linux task calculation, the simple execution of periodic tasksA command that executes a task at some point in the future has at, batchThe command to run a task periodically is crontabThe execution results of these commands are sent to the user by mailSmtpThis protocol can only send mailPOP3 or IMAP4Is the protocol that removes the message from the mail serverMUAMail user agent users to send and receive messages from the tool programLinux Task

View logs in real time:Tail-f/var/log/cronShow Task Scheduler Bash#crontab-u username-l Edit bash#crontab-u username-e Content: * * * * * commandline meaning: #分钟0-59 | Hours 0-23 | Date 1-31 | Month 1-12 | Day of the Week 0-6# * * * * *sample:0 */2 * * */sbin/service httpd restart30 6 */10 * ls means 1, 11, 21, 31st of the Month is The 6:30 executes the LS command onceRestart: Bash#service crond Restart Orbash#/etc/init.d/crond restart

/bin/systemctl Stop sshd0 * */5 * */usr/bin/rm-rf/var/ftp/pub/ *30 7 * * 6/USR/BIN/SYTEMCTL Restart HTTPD30 * * 1,3,5/usr/bin/tar JCVF HTTPDCONF.TAR.BZ2/ETC/HTTPDNote: When setting a task that is not performed every minute, the Minutes field should also fill in a specific time value instead of the default "*", otherwise the scheduled task will be executed every minute.Confirm the contents of the root user's scheduled task list[[email protected] etc]# CRONTAB-L50 7 * * */USR/BIN/SYSTEMCTL Start S