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

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1answer
223 views

Are threads which are executing blocking system calls awoken by interrupts?

I've been reading a bit about threads and interrupts. And there is a sections which says that parallel programing using threads is simpler because we don't have to worry about interrupts. However, ...
2
votes
3answers
528 views

How can I schedule a python program to run from another python program?

I'm running a Python program on my Linux server, and depending on some external data it has to run again at xx minutes or hours from now. So let's say it runs at 6 AM, and then it has to run again at ...
2
votes
1answer
233 views

What makes the Linux scheduler seem unpredictable?

The question refers to the output of a multi-threaded application, where each thread merely prints its ID (user assigned number) on the standard output. Here all threads have equal priority and ...
-3
votes
2answers
88 views

Which Linux distro/mode offers lowest interference when running your own applications?

I'm interested in a Linux distro to build C projects and test their behavior in a very predictable and controlled environment. I'm especially concerned about letting the scheduler deal as much as ...
2
votes
3answers
400 views

scheduling background tasks in succession

I've got three SAS programs to run in the background over a weekend. The three programs output information into files of the same names, so I'll need to remove these output files after the first ...
5
votes
2answers
2k views

Is there a workaround for a lack of scheduler in qbittorrent?

Unlike many other torrent clients, qbittorrent comes without a scheduling tool. Ideally, one can throttle downloads over a certain time of the day, on given days. Is there a workaround for this? Is ...
1
vote
0answers
94 views

at daemon creates empty tasks

I have problem with atd daemon. If at is called by non-root, it creates task, but it is empty (content of /var/spool/atd). I do not remember what I have done before it broke that way. What else ...
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vote
0answers
112 views

Client-server app for sending and monitoring asynchronous jobs

I am looking for a desktop app/IDE in which you can: Maintain a list of UNIX/Linux connections Be able to write a script locally in a local editor, not SCP files to the host or writing them on the ...
0
votes
1answer
293 views

How to make a scheduled task based on a file creation time?

The supercomputer I run my Analysis uses SGE to do the job management and requires each job duration not longer than 24 hours. And this feature is causing me quite a headache. Sadly, I was asked to ...
2
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1answer
1k views

controlling priority of applications using cgroups

I would like to understand cgroups better and would like to understand the use-cases for applying cgroups. Are cgroups a good way for prioritizing different applications (i.e, giving higher priority ...
4
votes
2answers
997 views

How preemption works on Linux when a program has a timer less then 4ms?

Jiffies in most Linux system are defaulted to 250 (4ms). The questions is that what happens when a program has a usleep() less then 4ms ? Of course it works as should when it is scheduled. But what ...
6
votes
1answer
455 views

Why mkfifo behaves like a LIFO?

If i do. mkfifo /tmp/a echo 'one'>/tmp/a in the while from another terminal echo 'two'>/tmp/a and from a third terminal more /tmp/a Why i obtain as output of the last command this? ...
3
votes
3answers
1k views

Bash while loop and reading from pipe

I have a Windows command-line program that I'm running in a Bash script in Ubuntu via wine. The Bash script basically looks like this: wine myprogram.exe | while read line do # Process line done ...
2
votes
3answers
2k views

Conditional crontab command in bash script

How do I invoke a crontab command so that I can schedule to run a script with a 20 minute delay based on some condition? Edit: What if I wanted a command that schedules a script to be executed only ...
4
votes
4answers
743 views

How to prevent atd from running past jobs?

The at daemon is a great tool! However, if a job is scheduled for 8:00 am and the machine is off at that time, at will run the job whenever the machine is booted. What I would like to do is stop it ...
6
votes
2answers
1k views

Does Linux kernel 3.x use the CFS process scheduler?

Does the latest version of the Linux kernel (3.x) still use the Completely Fair Scheduler (CFS) for process scheduling which was introduced in 2.6.x ? If it doesn't, which one does it use, and how ...
3
votes
1answer
301 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 ...
8
votes
1answer
707 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 ...
13
votes
2answers
654 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 ...
7
votes
2answers
2k views

How can you determine which process scheduler is being used? [duplicate]

I.e. is it the O(1) scheduler, the CFS scheduler, or an older one?
3
votes
2answers
471 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
2k 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 ...
11
votes
2answers
309 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
223 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
644 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
314 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
469 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
3k 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
568 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 ...
6
votes
3answers
661 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
417 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
462 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
2k 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
333 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
909 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
244 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
610 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
7k 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 ...
12
votes
2answers
43k 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 ...
7
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
306 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 ...
6
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
629 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
444 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 ...
30
votes
8answers
51k 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?