Questions tagged [scheduling]

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

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3
votes
1answer
729 views

How to reschedule an at job to run earlier?

Suppose I had scheduled an at job to run 3 hours later: $ echo command | at now +3 hours $ atq 9 Mon Dec 5 14:00:00 2016 a nr but having passed 1 hour I change my mind, and then need to run ...
0
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1answer
54 views

Does my scheduled task using “at” command run if I am logged out?

I knew cron still runs, but how about at? Checked with man at, but it didn't mention it.
2
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2answers
14k views

Check file is present and it is not empty

I want to check the file xx_x__x.log is present in the location or the file size is 0 at every Sunday 2:30am. I have a script to check file size and to check that it exists but I don't know how to ...
4
votes
4answers
17k views

@hourly vs 0 * * * * - Cron - How to run jobs hourly, but at different times

I have jobs that I want to run hourly, but not necessarily at the same time, which I think 0 * * * * job Means run at the 0 minute of every hour on the dot. I know I can also use @hourly job ...
2
votes
1answer
600 views

what is Linux global scheduling policy?

I am learning operating systems. I have a doubt. For example if scheduling policy for some set of process(set 1) is SCHED_RR and scheduling policy for some other set of processes(set 2) is SCHED_FIFO ....
1
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1answer
43 views

Running jobs based on changing time

I have a cron job that runs at 1am everyday that creates two files in /tmp, called firstrun and endrun, each containing the time that a script should be run. Once in the morning and once at night. ...
1
vote
1answer
43 views

Daily Cron for a month in Debian

How to make a Daily Cron only for a month? I want to run a certain command everyday at 2PM but want to run It only for a month, and after the month it should stop on its own. How to make it?
4
votes
1answer
1k views

realtime pthread created from non-realtime thread with init.d

I have a piece of C++ code that runs just fine when I run it from a Linux terminal, but which throws an EPERM error when run from a SystemV (init.d) script on bootup. The error comes from a ...
0
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1answer
432 views

Linux context switch internals: What happens when process exits before timer interrupt?

How is context switch made in linux kernel when process exits before timer interrupt? I know that if the process is running and timer interrupt occurs then schedule function is called automatically ...
-1
votes
1answer
39 views

Schedule a job to dynamically kill a (truss) process after a minute?

I have been trying to accomplish a simple scheduled task in Solaris 11 with the use of the at command. Example: $> kill $(ps -ef | grep -v grep | grep truss | awk '{print $2}') | at now + 1 ...
-1
votes
1answer
750 views

Schedule a shell script every day at 13 CET without crontab

I am developing a ksh shell script in AIX server which have to be exactly run at 13:00 on every day. I don't have permission to use CRONTAB, AT, WATCH, inotify, date -d, etc. The only option is use to ...
1
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0answers
130 views

Concurrent guest vcpu operation on KVM

I am launching an x86 debian system as guest using QEMU2.6.0 on my x86 host machine. The host is an 8-core, 2-socket machine booted with RHEL7 with KVM enabled. 2 PCI devices are being emulated on ...
-2
votes
1answer
5k views

at command not found [closed]

Following on from Cron job for 7 days alone not followed by multiple weeks, I am trying to use at but it shows at: command not found. By default it seems that Red Hat Enterprise Linux Server release ...
0
votes
1answer
228 views

Cron job for 7 days alone not followed by multiple weeks

I need to execute a cronjob to run once for 7 days alone. I have tried like this: 0 0 * * 0-6 myscript.sh It gets run for once a day and running every day of the week since I gave as 0-6. But I ...
3
votes
1answer
415 views

Zsh clear command line from zsh/sched call

I try the following: clear-cmdline() { zle && zle kill-buffer sched +3 clear-cmdline } sched +3 clear-cmdline After I run this code, I enter a few letters at prompt, and wait. ...
0
votes
1answer
109 views

Why top doesn't list my application as real-time?

I am trying to learn the scheduling policy on Linux with a small C++ application. The same should be valid for C. I am changing the priority of my app using the code below: sched_param tParam; ...
1
vote
1answer
572 views

How verify the current scheduling policy running in a embedded Linux?

I am testing a ARM based embedded target running with customized embedded linux version 3.14. Is there any way that I can find out which scheduling policy my linux is using at runtime? I see some /...
1
vote
1answer
280 views

Why Write looks to be prioritized over Read in file system? (or vice versa)

I am checking whether the linux file system i/o scheduler prioritizes the write operation over the read operation. The linux version is 3.10.0-327.el7.x86_64 I performed the following experiments ...
1
vote
1answer
197 views

Does a VM guest system runs only when the VM's process is scheduled on the host?

I'm working on preparing an enterprise software package for running on the cloud, but I'm facing the issue that the software package runs as a real-time process on our current deployments. No one is ...
1
vote
0answers
172 views

Using cgroups to write a job scheduler

One problem with cron is that if there are more jobs that can reasonably be run at a certain time, cron doesn't care: it will happily spawn the jobs anyway resulting in poor performance for all of ...
1
vote
1answer
113 views

Can the 0th physical core used asymmetrically on linux?

In an SMP and with a fair scheduling algorithm I'd expect all physical cores of a machine to get used evenly by linux. In theory I believe this is the case, but in practice I suspect not. Does ...
2
votes
2answers
1k views

linux: Is there a way to dump the task run queue?

I'm facing a strange extreme load issue on idle conditions. Is there a way to directly dump the linux process scheduler run queue? E.g. when sar -q outputs 400 as runq-sz, to get those 400 PIDs? ps,...
1
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0answers
485 views

Set GRUB `elevator=deadline` scheduling to a single device

I'd like to set my secondary drive to deadline. Is it possible to do it via GRUB, but leaving the primary drive as cfq? A script after booting would suffice in my case, but I'm interested in the GRUB ...
1
vote
2answers
622 views

What the heck is going on with my cron scheduler? (rsnapshot)

CRONTABS I'm using rsnapshot with cron. Here's what sudo crontab -l shows me. 0 */4 * * * /usr/bin/rsnapshot hourly 30 3 * * * /usr/bin/rsnapshot daily 0 3 * * 1 ...
1
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0answers
706 views

Round Robin vs FIFO

recently I had to do some reports about scheduling processes in Linux, and to do so, we were asked to turn off all cpu except 0 to show how processes are running for cpu. But there is one thing which ...
6
votes
1answer
63 views

Does linux stops processing related to GUI when we remove the desktop screen from connection from cabinet(CPU box)?

When there is big non interactive software running and if I required more processing power then, after removing the desktop screen does kernel stops processing related to GUI(graphical user interface) ...
1
vote
2answers
52 views

Can making CPU-intensive processes lowest priority (19) have adverse effects?

When I make a CPU-intensive process lowest priority (niceness of 19), it seems the amount of real memory consumption goes up. Perhaps this has other causes. But, can making CPU-intensive processes ...
4
votes
1answer
354 views

Why is nice-level ignored? (Between different login sessions — honoured if started from same session.)

When I start two CPU-eating processes with different nice-level, e.g. Process 1: nice -19 sh -c 'while true; do :; done' Process 2: sh -c 'while :; do true; done' (I changed the order of : and ...
3
votes
1answer
153 views

Process running in only one processor

I have a 40 v core machine in which a java process running. I can see that this process is running in cpu6 all the time. $watch ps -o pid,psr,comm -p 4076 Every 2.0s: ps -o pid,psr,comm -p 4076 ...
0
votes
1answer
440 views

`cpulimit` and `nice` not effective in limiting the cpu usage of a python program that contains heavvy computations using theano

I am running a program written in python that makes heavy computations using theano. As it is a very CPU-intensive program, it is disrupting all my other activies on my laptop. For this reason I ...
-3
votes
1answer
650 views

Informatica job scheduling scripting in unix

There are 4 shell scripts: Migrate a file from path-A to path-B (unix). This script triggers one powercenter work flow. This script triggers one IDQ job. This script deletes the file from path-B (...
7
votes
3answers
5k views

How does Linux kernel find out which process to wake up during interrupt handling?

I was reading the book Linux Kernel Development on Chapter Process Scheduling. On Page 61, section Waking Up, the first paragraph reads: Waking is handled via wake_up(), which wakes up all the ...
12
votes
3answers
10k views

Start/stop a systemd.service at specific times

I want to start and stop a systemd.service at specific times. Presumably I will use a .timer unit to start the job, but is there a built in way to stop the job after a specific duration, or at a ...
2
votes
2answers
879 views

How to setup an invisible cron job?

Is there a way to schedule a task using crontab by root user but should not be visible using crontab command i.e, crontab -l either for root user or normal users?
3
votes
3answers
740 views

Process scheduling data on linux

I am doing a project on OS and require the process scheduling data for an operating system. The data has to include the list of all processes in short-term-scheduler and long-term-scheduler along with ...
3
votes
1answer
801 views

Job queueing on a single machine

I have a shiny new server for running simulations on, with a pair of Tesla GPUs and 32 cores, running CentOS 7.2. I'd like for multiple users to be able to submit jobs to the server that get queued up ...
2
votes
1answer
2k views

Understanding Linux Perf sched-switch and context-switches

I've been trying to enable context switch events on perf and use perf script's dump from perf.data to investigate thread blocked time. So far the only two recording options that seem to be helpful ...
2
votes
1answer
953 views

Cron Job Hourly Except Certain Time Frame on Friday

I want my cron job to run every hour, every day except Friday when I don't want it to run at all between the hours of 2am-9am (but hourly outside of this timeframe). Ideally, I'd like to have this in ...
0
votes
1answer
80 views

nice command behavior when only 1 function running

I just learned the existence of nice (and ionice) which seems to be really interesting. I just want to launch a process 'p_low' with less priority than my ususal one 'p_normal'. What I was able to ...
0
votes
1answer
370 views

Get PID of scheduled job (using at)?

Say I want to schedule this job to be run at later time MYPROGRAM > output.out 2> error.err | at 02:00 PM Mon How can I attain its PID? Surely using: echo $! will not work?
0
votes
1answer
866 views

Schedule a job to run in the background ( one time task scheduling using at )

Is it possible to request for a job to be run at a later specifed time in the background? This is what I have so far, nohup nice MY_PROGRAM > foo.out 2> foo.err < /dev/null | at 05:23 PM ...
3
votes
0answers
491 views

System time in Minix with best precision

I'm working on a project to modify the scheduler in MINIX 3. So to test it I need to analyse the wait time and turnaround time. To calculate the wait time I'm storing the system time when the process ...
4
votes
2answers
894 views

How does the Linux scheduler determine if a process is I/O bound or CPU bound

Adding to this question, how does the scheduler determine if a process is I/O bound or CPU bound? Mr. Love in this article, says "schedulers often employ complex algorithms to determine the most ...
1
vote
0answers
293 views

Process scheduling and core allocation on big.LITTLE CPUs

Recent ARM chips, like the Qualcomm Snapdragon 810, seem to be using a hybrid architecture called "big.LITTLE" with cores of different architectures and speeds combined into one CPU. On a Linux (or ...
2
votes
1answer
68 views

How to schedule task to run everyday, if I don't know when the pc will be turned on?

So, I could use the crontab command, with: 23 0 * ... but at 23:00 my laptop can be turned off, or hibernated. In that case I want a command to be executed as soon as it will be possible. How can ...
-1
votes
1answer
4k views

Cron task scheduling and stopping after certain interval [closed]

I am managing a server which has multiple cron tasks, one of the crontab entry is like below: 51 ​*/2 *​ * * /root/backup.sh can anyone explain me what is happening here, at what time the script is ...
2
votes
1answer
258 views

Is “top” accounting for Kernel Interrupts?

I have a simple interrupt that is triggered by a GPIO-input. The IRQ only increments a variable and returns. When I turn the frequency of the interrupts up to somewhere around 10-20 kHz, the system ...
2
votes
1answer
730 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 ...
1
vote
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 ...
1
vote
3answers
4k 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 ...