Limiting the usage of a resource (memory, disk space, CPU time, open files, network bandwidth, …) by a process or a group of processes.

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22
votes
4answers
2k views

How to limit resource usage to save CPU+RAM for a certain process?

I have a dev server on which sshd sometimes stops working because the machine runs out of RAM. Yes we are running low on memory and upgrading is not a feasible choice right now. What I want to do is ...
20
votes
3answers
1k views

Can the “du” program be made less aggressive?

We have a regular job that does du summaries of a number of subdirectories, picking out worst offenders, and use the output to find if there are things that are rapidly rising to spot potential ...
18
votes
3answers
12k views

Why is number of open files limited in Linux?

Right now, I know that: Find open files limit per process: ulimit -n Count all opened files by all process: lsof | wc -l Get maximum open files count allowd: cat /proc/sys/fs/file-max My ...
17
votes
2answers
17k views

Limit process to one cpu core

How to limit process to one cpu core ? Something similar to ulimit or cpulimit would be nice. (Just to ensure: I do NOT want to limit percentage usage or time of execution. I want to force app (with ...
15
votes
6answers
5k views

Is there a way to limit the amount of memory a particular process can use in Unix?

I need to test a process for memory management. I do not have the source, so I need to do all the testing from the OS side. I want to be able to say something like limitmemory 400k -p <pid> ...
15
votes
3answers
625 views

Limiting a specific shell's internet bandwidth usage

I want update my linux in one shell but by default wget or axel in updater use all the bandwidth. How can I limit the speed in this shell? I want other shells to have a fair share, and to limit ...
12
votes
2answers
12k views

How to create a user with limited RAM usage?

So I have 4 GB RAM + 4GB swap. I want to create a user with limited ram and swap: 3 GB RAM and 1 GB swap. Is such thing possible? Is it possible to start applications with limited RAM and swap ...
12
votes
3answers
3k views

Can I limit a process to a certain amount of time / CPU cycles?

We have a script which runs on our web servers, triggered by customer action, which initiates a unix process to generate some cache files. Because this process acts upon files supplied by our ...
11
votes
2answers
931 views

Is there an upper limit to the number of zombie processes you can have?

I used to work with an HP-UX system and the old admin told me there is an upper limit on the number of zombie processes you can have on the system, I believe 1024. Is this a hard fact ceiling? I ...
10
votes
5answers
7k views

How to limit log file size using >>

How can I limit the size of a log file written with >> to 200MB? $ run_program >> myprogram.log
10
votes
2answers
5k views

How to Throttle per process I/O to a max limit?

I'm looking for a way to limit a processes disk io to a set speed limit. Ideally the program would work similar to this: $ limitio --pid 32423 --write-limit 1M Limiting process 32423 to 1 megabyte ...
9
votes
6answers
2k views

How do I set a limit on the number of files Linux can have open?

I plan to run a Java app using nohup ... &. The limit must apply to commands like this.
9
votes
2answers
557 views

How to solve this memory issue gracefully?

I have a standard Linux (Debian testing) laptop, with a swap partition. I do a lot of experiments with it. Some of them are really memory hungry and the way Linux behaves by default is an issue for ...
9
votes
1answer
55 views

Limit on the number of btrfs snapshots?

I am considering using btrfs on my data drive so that I can use snapper, or something like snapper, to take time based snapshots. I believe this will let me browse old versions of my data. This would ...
8
votes
4answers
6k views

How do I limit the number of files printed by ls?

Is there a way to limit the quantity of listed files on a ls command? I've seen: ls | head -4 but to get head to be executed I need to wait for ls to finish execution, and with directories with an ...
8
votes
2answers
5k views

How to limit available virtual memory per process

Occasionally some processes on my GNU/Linux desktop (such as gv and gnash) use up the physical memory and cause thrashing. Since these processes aren't important, I want them to be automatically ...
8
votes
1answer
229 views

How to limit the total resources (memory) of a process and its children

There are plenty of questions and answers about constraining the resources of a single process, e.g. RLIMIT_AS can be used to constrain the maximum memory allocated by a process that can be seen as ...
7
votes
3answers
353 views

Limit max connections per IP address and new connections per second with iptables

We have an Ubuntu 12.04 server with httpd on port 80 and we want to limit: the maximum connections per IP address to httpd to 10 the maximum new connections per second to httpd to 150 How can we ...
7
votes
1answer
2k views

Throttling web crawlers

My website is being DoS'ed by Google webspiders. Google is welcome to index my site, but sometimes it is querying a tagcloud on my site faster than my webserver can produce the results, making my ...
6
votes
7answers
611 views

Make disk/disk copy slower

Is there a method of slowing down the copy process on Linux? I have a big file, say 10GB, and I'd like to copy it to another directory, but I don't want to copy it with full speed. Let's say I'd like ...
6
votes
3answers
11k views

do changes in /etc/security/limits.conf require a reboot?

do changes in /etc/security/limits.conf require a reboot before taking effect? Like if I have a script that sets the following limits in /etc/security/limits.conf, does this require me to reboot ...
6
votes
1answer
106 views

Do processes in cgroups have to be set every boot? If so, how to persist them?

I was reading this answer to a question on setting limits for processes by using cgroups. The sample given sets limits for a process (in the example, sshd). In the answer, the PID of the process is ...
6
votes
1answer
1k views

Are limits.conf values applied on a per-process basis?

I'm tuning the nofile value in /etc/security/limits.conf for my oracle user and I have a question about its behavior: does nofile limit the total number of files the user can have open for all of its ...
6
votes
2answers
609 views

What is a canonical way to find the actual maximum argument list length?

Following ARG_MAX, maximum length of arguments for a new process it seems like ARG_MAX is wrongly (or at least ambiguously) defined on my Mac Mini 3,1 running Ubuntu 12.04: $ getconf ARG_MAX # ...
5
votes
1answer
233 views

Why is the following command killing a system?

Anyone understand the following code , running in bash ? :(){ :|:& };: It seems to be a "fork" bomb on Linux.
5
votes
4answers
4k views

Preventing tar from using too much CPU and disk (old laptop crashes if 100%)

I want to backup 1 terabyte of data to an external disk. I am using this command: tar cf /media/MYDISK/backup.tar mydata PROBLEM: My poor laptop freezes and crashes whenever I use 100% CPU or 100% ...
5
votes
1answer
1k views

How many users does Linux support being logged in at the same time via SSH?

I know Linux supports multiple users being logged in at the same time. But what's the maximum number of users that can be logged into Linux at the same time? I see there are there are 69 tty files ...
5
votes
2answers
313 views

How can I allow a user to prioritize a process to negative niceness?

I want a user to run a specific process on the system with a negative nice value. I can't simply fork the process to background as this specific program is a minecraft server and I rely on the command ...
5
votes
2answers
508 views

Does linux kill heavy and long running background processes after they reach some threshold?

If I start a really heavy (memory/cpu intensive) running really long running process will the OS terminate it after a period of time arbitrarily? I.e. are there any limits beyond which the OS would ...
5
votes
1answer
2k views

How to circumvent “Too many open files” in debian

If I want to see all relevant log files of my apache2 server at once, I use tail -f /var/kunden/logs/*log /var/kunden/logs/*log /var/log/apache2/*log |grep -v robots|grep -v favicon But since those ...
5
votes
2answers
4k views

ulimit PICKLE: “Operation not permitted” and “Command not found”

I'm trying to increase the maximum number of open files for the current user > ulimit -n 1024 I attempt to increase and fail as follows > ulimit -n 4096 bash: ulimit: open files: cannot ...
5
votes
2answers
5k views

Set default nice value for a given user (limits.conf)

Could someone tell me how to set the default value of nice (as displayed by top) of a user? I have found that /etc/security/limits.conf is the place but if I put either: username_of_a_guy - nice ...
5
votes
1answer
1k views

File descriptor limits are lost after a system reboot

I'm trying to increase the default file descriptor limits for processes on my system. Specifically I'm trying to get the limits to apply to the Condor daemon and its sub-processes when the machine ...
4
votes
2answers
5k views

Modify ulimit (open files) of a specific process

Is it possible to change the soft - and hard limit of a specific process? In my case, my process is mongod and a lot of web resources tell me to simply execute: ulimit -n <my new value> My ...
4
votes
1answer
121 views

FILE size limitation according to Robert Love's textbook

From Robert Love's Linux System Programming (2007, O'Reilly), this is what is given in the first paragraph (Chapter 1, Page 10): The file position’s maximum value is bounded only by the size of ...
4
votes
2answers
1k views

What is “automatic stack expansion”?

getrlimit(2) has the following definition in the man pages: RLIMIT_AS The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2) and ...
4
votes
2answers
185 views

Externaly limiting number of CPU cores used

I need to externally limit a process/session to a certain number of cores. Are there any other possibilities than CPU affinity (I don't like the need to specify the actual cores) and cgroups (hard to ...
4
votes
1answer
811 views

Linux - why is kernel.shmall so low by default?

I run DB2 on Linux where I have to allocate the vast majority of memory on the machine to shared memory segments. This page is typical of the info that I've found about shmall/shmmax: ...
4
votes
2answers
388 views

Does OpenBSD have a limit to the number of file descriptors?

What's the maximum number of file descriptors that a process can get on OpenBSD successfully? For example, there is an openfiles limit in login.conf(5) in OpenBSD. If I want to have as many file ...
3
votes
1answer
553 views

Httpd : no space left on device

I am using Fedora 17 and over the last few days I am having an issue with my system. Whenever I try to start httpd it shows me: Error: No space left on device When I execute systemctl status ...
3
votes
1answer
39 views

Different between `ulimit -e` and `renice`?

I would like to run a backup script in low CPU and disk I/O. Is there any different between this: #!/bin/bash ulimit -e 19 ionice -c3 -p $$ and this: #!/bin/bash ionice -c3 -p $$ renice -n 19 ...
3
votes
3answers
828 views

limiting size of logfile from a variable

How can I limit the size of a log file, which is saved in the form of 'foo.txt', from within a bash script please? I want to put in the variables 'LOGFILE=50 mb' and it uses that size, or whatever ...
3
votes
1answer
5k views

How do I increase the number of semaphore arrays in Linux?

In a Debian lenny server running postgresql, I noticed that a lack of semaphore arrays is preventing Apache from starting up. Looking at the limits, I see 128 arrays used out of 128 arrays maximum, ...
3
votes
1answer
109 views

Increasing nproc limit for a non-root user . Only effective by restart

I am increasing nproc limit for one of a development user account in my rhel6 system . After searching some rubust solution , I zerod at editing /etc/security/limits.conf with these two lines : ...
3
votes
3answers
83 views

Why are file handles a scarce resource?

I feel like every tutorial I read on resource management in server settings starts by asserting that file handles are a scarce resource, and we should therefore aim to keep the list of open files to a ...
3
votes
3answers
752 views

Can't add large number of rules to iptables

I made a very simple bash script (echo at start, runs commands, echos at end) to add approx 7300 rules to iptables blocking much of China and Russia, however it gets through adding approximately 400 ...
3
votes
1answer
507 views

How do you increase MAXSYMLINKS

In a python script, I am creating a bunch of symbolic links chained together. example: link1->link2->link3->.......->somefile.txt I was wondering how you can change the max number of symlinks to be ...
3
votes
1answer
234 views

Control Dropbox upload rate on the command line

I'm using Dropbox without the GUI in Linux. I would like to limit the upload rate, sometimes large files eats my internet bandwidth. Anyone knows how I do that?
3
votes
1answer
332 views

Can I limit connections per second for certain UserAgents using UFW?

GoogleBot is hitting my server hard - and even though I have set the CrawlRate in Webmaster Tools it is still hiking up the load on my server and slowing down Apache for the rest of the normal web ...
3
votes
2answers
3k views

How to limit ftp speed

I have multiple user on a server, they upload and download their file through FTP, sometimes some heavy transfer make high load on server, I am wondering is there any way to limit ftp speed to avoid ...