Questions tagged [scheduling]

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

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737 views

Tuning Linux I/O Scheduler

I need a little help with properly tuning the Linux I/O Scheduler for spinning drives. I have a process that writes data to a huge (4-16TB) memory mapped file and is using SHED_FIFO. The kernel then ...
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1answer
2k views

iotop and ionice -p show a different class/priority for the same process

After running ionice -c2 -n7 <PID> on an I/O-intensive process (VirtualBox VM) and checking the result with ionice -p <PID> it shows best-effort: prio 7 which is expected. But when ...
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3answers
5k views

Excluding specific date and time in cronjob

I am trying to schedule a cron job where the requirement is the job has to run every day, every month and every min and every hour EXCEPT 2nd and 4th sunday of every month from 1 to 3 AM. Is there a ...
2
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1answer
3k views

cronjob at resume from suspend

using linux. I know you can do an @reboot cronjob. I want to do an equivalent thing but instead of running at reboot, running after my computer awakens from suspend. Is that possible?
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2answers
1k views

Run program x minutes after finishing

My question is kinda related to a cron job I think, but I'm not entirely sure. Say I have a script (/home/me/myscript.sh) that does something, that can take an indeterminate amount of time to finish, ...
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2answers
2k views

Why does niceness range from -20 to 19?

The nice command allows you to adjust the scheduling priority ("niceness") of a program. On all Unix-like systems I've used, niceness is specified by a range of integers, where -20 is the most ...
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1answer
950 views

Python script works from terminal, but fails in scheduler, to write to external drive

I am trying to use a Python script to read/write from an external disk in linux, which works fine. The problem comes when I use a job scheduler to execute the Python program. I am running all this on ...
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1answer
632 views

Are blocked and blocked/suspend processes put into the same queue?

In a 7-state process model (new, ready, blocked, running, blocked/suspend, blocked/ready, exit), are processes in the blocked and blocked/suspend states for each event that processes are blocked on ...
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3answers
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How can I verify `nice` is working?

Looking at different jobs running on a system with shared resources, it seems the nice values are being ignored. Many jobs with nice set at 19 are running at 100% cpu load while other many other jobs ...
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0answers
590 views

How to set a process’s sched method to fifo and priority when cgroup are on?

I’m using CentOS 6.6, I want to set the sched method of my kvm VM to FIFO with priority 1. First, I use chrt and get error: chrt(): "failed to set pid XXX's policy" I find here: chrt(): "...
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1answer
433 views

Why does Linux scheduler have locks for run queues?

Why does Linux Kernel Scheduler code have locks for run queues? Does the scheduler spawn kernel threads, and locks are to prevent two of such threads to avoid modifying run queues at the same time?
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1answer
420 views

Why doesn't the Linux kernel prioritize interactive programs?

I've noticed that when running at 100%, things like GNOME become less responsive until I kill background tasks that are expected to take a long time, like compilation or downloading email. Why doesn'...
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1answer
256 views

Why have the notion of 'nice'?

I know what 'nice' is and how it maps to priority, this is not the question. Linux priorities range from 0-139. 0-99 is real time, 100-139 is user space. Nice maps onto priority: -20 → 100 0 → 120 ...
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1answer
196 views

Midi and Scheduler on Linux / Raspberry Pi

I'm fairly new to MIDI and Linux. I have an Akai MPX8 with a bunch of individual WAV files loaded onto it. The WAV files play well over the existing audio system. The audio files are launched by ...
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0answers
147 views

CPU Scheduling incredibly slow with large difference between total execution time and actual CPU time - Ubuntu Full-Disk Encryption enabled

Admittedly, I am running on a build that is no younger than five years old at this point and the system is not going to be incredibly fast. However, at the same time, the run-times I am observing are ...
3
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1answer
7k views

How to schedule shutdown every day?

We have a server that is used for Linux thin clients in a class. The server is started when required and I want to schedule it to power off at 22:00 every day to avoid power wasting. I thought of ...
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2answers
3k views

Why sudo user can use sched_setscheduler SCHED_RR while root can not?

I am running Arch Linux on a Raspberry Pi 2. I have a user-space program that uses Gordon's wiringPi library and, in particular, the piHiPri() function that attempts to set the highest priority for ...
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3answers
3k views

how to tell crontab to execute the command from now instantly

I have a command in "/etc/crontab" which runs a database program every 7 days. Now, I see that this command has been commented by another user for 2 weeks. I immediately uncommented the line, and ...
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1answer
196 views

How to skip email notification for at command in AIX?

(AIX 6.1 ) man page for at says -m option could send an email to the user. But this is the default behavior, even without specifying the -m option. Is there a way to turn this off, I do not want mails ...
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1answer
2k views

Relationship between IO scheduler and cpu/process scheduler?

The concepts of IO scheduler and CPU scheduler confuse me. Below are my understanding: Linux uses CFS scheduler + nice values by default to schedule processes. Each process has an IO queue. There ...
18
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2answers
21k views

Run script every 30 min with systemd

I would like to execute a script every 30 min after booting into the system. I know you can use cron, but I don't plan to use this feature often therefore I'd like to try it with systemd. So far I ...
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4answers
1k views

cron - production-ready alternative

I am testing out a Raspberry Pi with the aim to use it in a production system for logging manufacturing data. All is working well and I have been recording test data over the last month. For ...
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0answers
1k views

Catch the kill signal when a process is in S state [interruptible sleep]

This is the process group : (ps -ejH) xxxx xxxx xxxx ? 00:00:00 sshd yyyy yyyy yyyy ? 00:00:00 sshd 8713 8713 8713 pts/0 00:00:00 bash 1234 1234 1234 ? ...
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1answer
68 views

Scheduling gFTP Download

My current set up involved two HP laptops running Linux Mint 13 (one 32-bit, the other 64-bit) and a Mint 13 server in the cloud. I have been using gFTP for transferring files without problem. However ...
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4answers
16k views

Is there a way to auto turn-on Linux machine?

I know that there are many ways to auto-shutdown, but I'm concerned about auto turn-on. Is there a command or a small piece of software to turn on the system at given time?
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1answer
39 views

Is there a good reason to prevent users from using cron/at?

At work on our linux servers, I have a standard non root account. Unfortunately the account does not have permissions to crontab or at. Is there a good reason to block these commands? I can write a ...
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1answer
2k views

What is the functionality of SCHED_SOFTIRQ in linux?

Who raises this softirq? Is it raised on every time tick( based on timer interrupt?) Does this make the kernel to shedule a runnable process? If yes, how does the handlers of lower priority softirqs ...
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1answer
842 views

Supervisord scheduling [closed]

Is it possible to set jobs to run every n days in supervisord, like what cron is doing? I'm asking because I have different kinds of jobs, continuous / real-time and daily ones. All my jobs are ...
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1answer
52 views

take the DRAM performance of the processes into consideration when scheduling

The CFS scheduler in Linux schedules the processes based on the virtual runtime of CPU. But, the DRAM memory is the bottleneck in most of the emerging domains. Why not take the DRAM performance of ...
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0answers
44 views

expanding the priorities table in runqueue in Linux kernel

I have a hw assignment that I'm having really hard time with, probably since I'm new to the whole Linux kernel thing. we're supposed to add a new scheduling policy to the existing scheduling ...
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0answers
58 views

Linux Fedora 20: how can I find out what is happening behind the scenes

I have Fedora 20 installed, using MATE desktop and zshell and something weird is going on. I get lots of odd unexplained beeps from my speakers, even though the volume is turned down to zero, so ...
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6answers
3k views

Can you make a linux system halt and boot my Raspberry-pi at certain times?

How to make a system turn itself off and back on at different times. For example I would have my "server" turn off at 4 A.M then turn back on at 5 A.M every day. Is this possible? I am using a ...
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0answers
47 views

Spawning processes on a job stack

I have a hobbyist server on which I want users to upload a file, and then receive the overcome of some processing (server-side) over the given file. I am doing the processing synchronously so that for ...
3
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1answer
575 views

Configure job to expire

I'm learning Linux at the moment and were doing some exercises scheduling jobs with cron and crontab, but I'm wondering if it's possible to limit the amount of times that the scheduled job is ran. ...
3
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1answer
764 views

Thread process in linux

I'm wondering about the "punishment" that occurs when a new thread is created. From my understanding of clone(2), NPTL (New POSIX Thread Library), CFS (Completely Fair Scheduler), when a new thread ...
3
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1answer
995 views

Why does the 'user' and 'sys' time vary on multiple executions?

There is a nice question and answer explaining the relationships between 'real', 'user' and 'sys'. It explains the reasons why 'real' can vary, and defines the 'user' and 'sys' as times the process ...
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1answer
49 views

Run program while computer is cool

I'm trying to compile a program on a computer with inadequate cooling. The program, specifically, is the linux-ck kernel with -mtune=native march=native processor-specific optimizations, so simply ...
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1answer
145 views

High precision scheduler daemon

I'm looking for a scheduler daemon like cron, but with at least seconds precision so I can use it for a radio automation app. I've heard conflicting rumors about cron's ability to handle seconds. If ...
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0answers
4k views

Does the timeslice depend on process priority or not under Completely Fair Scheduling?

I'm trying to understand the Completely Fair Scheduler (CFS). According to Robert Love in Linux Kernel Development, 3rd edition(italics his, bold mine): Rather than assign each process a timeslice,...
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2answers
2k views

How is the real-time priority of a process set by default?

I understand that, for scheduling purposes, Linux processes have a "nice" value and a real-time priority value and that these can be explicitly altered with the nice and chrt commands. If the user ...
6
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1answer
679 views

Is the Unix process scheduler itself a process?

Is the Unix process scheduler itself a process, or does it piggyback on other processes in the same way a system call does (running kernel code in the user process with the kernel bit set)?
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1answer
27k views

Real time processes scheduling in Linux

I have been learning some scheduling concepts. Currently my understanding so far is as below. There are real time processes and non real time processes. Non real time processes can have nice values ...
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1answer
11k views

Why highest priority threads are displayed with RT in top and htop?

In the top and htop tools, processes (or/and threads depending on display settings) having the highest realtime priority (99 from the userland API point of view) with either the scheduling policy ...
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2answers
81 views

How do I make “at”-tasks repeat at a specific time?

I want to schedule a script to run every Monday at 9am. How can I do this? I can only find examples for given days, not repeating things with at. Cron is not a solution.
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1answer
441 views

What does a computer actually do with its spare CPU cycles?

When a computer is not running at full load, in the context of Linux, what does it actually do? Between scheduled threads, if there is nothing to do, does it spin wait? Does it enter some sleep state? ...
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2answers
1k views

How to set cron job for system

I'm really new on Linux and have no any previous experience on it. And I opened this account to ask this question. I need to install a cron job I've followed the short guide here. Well, I think it ...
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1answer
255 views

What is the scheduling algorithm of the Native POSIX Thread Library?

According to Wikipedia, The Native POSIX Thread Library (NPTL) is: a software feature that enables the Linux kernel to run programs written to use POSIX Threads efficiently. Which algorithm is ...
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1answer
1k views

Which process scheduling algorithm is used by Linux?

The Linux operating system switches between running processes to enable multi-tasking. What algorithm is used to determine when to suspend the execution of the currently running process and which ...
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0answers
931 views

What is the minimum round robin scheduing interval supported by Linux?

For some reason, I want to have 10 processes share the same CPU core by affinity. As you know, to achieve CPU sharing between processes, we can exploit the Linux round robin (RR) scheduling policy. ...
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2answers
2k views

Schedule job at irregular intervals

It's simple enough to use cron to schedule a job to occur periodically. I'd like to have something occur less regularly -- say, run the job, then wait 2 to 12 hours before trying again. (Any ...