A technique for scheduling tasks to be run at a specific time or on a specific event.

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3
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1answer
251 views

Unix/Linux process scheduler logs

Where can I actually see what decisions did a process scheduler make over a time period? Are there scheduling specific logs maintained by Unix/Linux systems I could take a look or should I be looking ...
7
votes
1answer
596 views

Why can a system become unresponsive?

I just executed dot (a program for drawing directed graphs) with an input file that was so big that it couldn't be rendered in a reasonable amount of time. My whole system froze. I could barely make ...
12
votes
2answers
598 views

What is a simple way to schedule a single event to happen at some time in the future?

There are often times that I want my computer to do a single task, but not right now. For example, I could have it notify me in 30 minutes that it is time to leave work. Or maybe I want it to run a ...
23
votes
1answer
2k views

High CPU usage with CFS?

I asked a previous question to try and isolate the source of an increase in CPU usage when moving an application from RHEL 5 to RHEL 6. The analysis that I did for that seems to indicate that it is ...
8
votes
1answer
3k views

Isolating cause of higher CPU usage on RHEL 6 vs RHEL 5

I'm currently looking to move our system from RHEL 5 to RHEL 6, but I've run into a snag with unexpectedly high CPU usage on the RHEL 6 machines. It appears that this may be due at least in some part ...
6
votes
2answers
1k views

How can you determine which process scheduler is being used?

I.e. is it the O(1) scheduler, the CFS scheduler, or an older one?
3
votes
2answers
467 views

How does a script/program executes in unix?

I have a doubt about the execution pattern of a unix script. For example a script containing lines: command B function C() { Myscript // Myscript is a script command D } command E and ...
3
votes
3answers
1k views

How to schedule something run once using anacron?

Frequently within my scripts I schedule auxiliary tasks for later in the form: at now + 8 hours <<< "rm -f workfile.$$ >> $worklog 2>&1 " or at 11pm + $(date +%M) minutes ...
10
votes
2answers
279 views

What are the effects, if any, of scheduler priorities and policies for threads in an uncontended cpuset?

I have a Linux system where we have used cgroups to create two cpu_exclusive cpusets, A and B, and where we have migrated all user threads and all unbound kernel threads to a cgroup attached to cpuset ...
7
votes
1answer
198 views

Prioritise X applications with focus

Is there a way to prioritise X applications with focus, preferably both in terms of CPU and I/O? Something like all X applications are niced and ioniced down in priority, but when they gain focus ...
2
votes
4answers
511 views

Is there any handy command line tool to manage Cron jobs?

Would someone suggest any handy command line (NOT web) tool or script which adds, enables and disables Cron jobs? I am looking, for example, for the following (or similar) behavior: sh manageCron.sh ...
2
votes
1answer
266 views

Get pid of long running command executed via at

I would like to spawn a persistent netcat server. My command of choice is the following: echo "bash -c \"while [ 1 ]; do nc -l -p 1111 >> check; done\"" | at now I am wondering how I can get ...
1
vote
1answer
415 views

Disk Scheduler in Linux

I am studying about Disk Scheduling in my OS class. Thought about the disk scheduler in Linux. When I run cat /sys/block/sda/queue/scheduler noop anticipatory deadline [cfq] Someone explain about ...
7
votes
3answers
2k views

Which Scheduling algorithm is used in Linux?

Recently in an interview I was asked about the Scheduling algorithm used by Linux Operating system. What is the algorithm used any why? Also, what algorithm is used in in real-time operating systems ...
3
votes
1answer
492 views

Scheduled task on reboot

How can I schedule a task to run on next reboot? I understand that we have tools like cron and at to help with scheduling. But they seem to allow scheduling at a specific time and not on specific ...
5
votes
3answers
434 views

Simple queuing system?

Given a commodity PC, we would like to use it to execute some tasks in the background round the clock. Basically, we would like to have commands like: add-task *insert command here* list-tasks ...
4
votes
3answers
337 views

GNU: Delayed jobs Queue

Is there a simple way for me to add a shell command to a list of jobs to have run on the system when I'm not logged in? For example: I SSH into my system, decide that I want to read an ebook later, ...
5
votes
1answer
428 views

Linux process scheduling - Cap/Weight based?

I am just trying to understand the basics of Linux scheduler. Is Linux scheduler a Cap based or weight based scheduler? I was previously using Xen. Now I am moving from Xen to KVM. I read VMs are ...
2
votes
1answer
1k views

What happens the most, context switches or mode switches?

Which happens the most, context switches or mode switches? I have two answers myself, but I do not know which one is correct: Context switches happen in user mode, but this does not mean that a ...
1
vote
4answers
318 views

Faster delayed execution than 1 minute?

I am working on a program that can "upgrade itself" by install a new package. In order to accomplish this, I am using the at command to specify that a shell script should be run one minute in the ...
2
votes
3answers
806 views

How to monitor or kill a process which has been started by cron?

I have some bots, which are run by the System scheduler at given time interval. But sometimes due to some logical error I have to stop these bots manually. How can I find these processes run by the ...
3
votes
3answers
213 views

Changing the disk scheduler on the fly

Can the Linux disk scheduler be changed on the fly by writing to /sys/block/sda/queue/scheduler? Should applications (e.g. Mysql) be stopped / started when changing?
3
votes
2answers
506 views

How do I execute a script later?

I need to compile gcc45 on my computer and that's a lengthy and resource-intensive process for my computer, so I'd prefer to have it do it while I sleep (at night). What's the closest thing to: $ ...
8
votes
2answers
5k views

Bash Script on Startup? (Linux)

Is there any way to make/run a bash script on reboot (like in Debian/Ubuntu for instance, since thats what my 2 boxes at home have) Also, any recommended guides for doing cron jobs? I'm completely ...
10
votes
2answers
26k views

How can get a list of all scheduled cron jobs on my machine?

My sysadmin has set up a bunch of cron jobs on my machine. I'd like to know exactly what is scheduled for what time. How can I get that list?
3
votes
2answers
2k views

Add a one-off scheduled task through a shell script?

I'd like to execute a task at a given time, once. I know I can just use crontab -e to add it there, but I'd like to do that through a shellscript. crontab -e gives me some temporary file to edit ...
5
votes
1answer
2k views

How can you schedule a computer to boot at a specific time?

Usually BIOSes have an option to schedule a time to which to boot at. Is there a Unix/Linux interface to specify the scheduled boot?
4
votes
1answer
267 views

Are there any Workload Management subsystems for Linux?

Asked this on superuser, got no response: Can anyone tell me of the status/state of WLM (Workload Management) kernel scheduler systems in Linux? Alternatively, any user-space process goal-based load ...
5
votes
1answer
1k views

How do I view the IO priority of a process?

How can I view the IO priority of a process? like to see for example if something has been ionice-ed.
8
votes
3answers
593 views

how to queue a command to run after another command finishes?

Sometimes I start a program that takes a very long time to finish (emerge), then realize that I should go to bed instead of waiting for it. If I know this in the first place I would run program; halt ...
6
votes
4answers
438 views

Scheduling commands by system inactivity

So cron or at can schedule our commands to run at the exact time we need them to, but can we schedule commands to run when systems are inactive? Something like: echo "some_commands" | when 'cpu ...
24
votes
7answers
36k views

Where are cron errors logged?

If I setup cron jobs incorrectly they appear to silently fail. Where should I look for an error log to understand what went wrong?