Systemd – Changing ulimit Settings

ulimit

I've found this link, showing how to change the ulimits on systemd.

/etc/systemd/system/<servicename>.d/override.conf
[Service]
LimitNOFILE=49152

I found a website suggesting to change the ulimits for systemd in these files:

/etc/systemd/system.conf
/etc/systemd/user.conf

[Manager] 
DefaultLimitNOFILE=49152

What's the difference between this two methods?
What's best practive?

Thanks for input.

Best Answer

/etc/systemd/[system|user].conf are used to define default values for service unit files.

As I suppose that you only want to change settings for a single unit file, the /etc/systemd/system/<servicename>.d/override.conf is the cleanest method, and definitively a best practice.

Related Solutions

Linux ulimit – Practical Maximum Open File Descriptors for High Volume Systems

These limits came from a time where multiple "normal" users (not apps) would share the server, and we needed ways to protect them from using too many resources.

They are very low for high performance servers and we generally set them to a very high number. (24k or so) If you need higher numbers, you also need to change the sysctl file-max option (generally limited to 40k on ubuntu and 70k on rhel) .

Setting ulimit:

# ulimit -n 99999

Sysctl max files:

#sysctl -w fs.file-max=100000

Also, and very important, you may need to check if your application has a memory/file descriptor leak. Use lsof to see all it has open to see if they are valid or not. Don't try to change your system to work around applications bugs.

Windows – ulimit for windows

windows system resource manager is the tool to set cpu limits per process, and adds process accounting interfaces. In older versions of windows this was what was on the second disk that no-one ever installed. In 2008 its a feature to be enabled. Its generally not as important on a windows system (from a resource control perspective) than a unix one as "nice" is built into the OS and process priority (with certain exceptions) can be changed on the fly in the gui, in addition under windows vist and above disk IO can also be prioritized (by default this is based off of the priority of the process). There is an API that lets you set disk IO priority explicitly but I am unaware of any utility to let you directly change just disk IO priority

Best Answer

Related Solutions

Linux ulimit – Practical Maximum Open File Descriptors for High Volume Systems

Windows – ulimit for windows

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