Re: [systemd-devel] MemoryLimit for user unit

[Lennart Poettering]

On So, 12.11.17 18:14, Stefan Schweter (ste...@schweter.it) wrote:

> Hi systemd-users,
> 
> I tried to add a memory limit for a user service unit (inspired by [1]),
> it looks like:
> 
> [Service]
> # 
> MemoryAccounting=true
> MemoryLimit=1G
> 
> Now the problem is that the (user) service consumes more than 1G without
> being terminated.

Note that on cgroupsv1 delegation of controllers to unprivileged
code is not safe and hence systemd won't do it. That means you have to
boot in cgroupsv2 mode (i.e. "unified") to get any controller support
at all for the user systemd instance.

Lennart

-- 
Lennart Poettering, Red Hat
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Re: [systemd-devel] MemoryLimit for user unit

[WaLyong Cho]

On 2017년 11월 13일 09:53, Kai Krakow wrote:
> Am Sun, 12 Nov 2017 18:14:38 +0100
> schrieb Stefan Schweter :
> 
>> Hi systemd-users,
>>
>> I tried to add a memory limit for a user service unit (inspired by
>> [1]), it looks like:
>>
>> [Service]
>> # 
>> MemoryAccounting=true
>> MemoryLimit=1G
>>
>> Now the problem is that the (user) service consumes more than 1G
>> without being terminated.
> 
> As far as I could see, this limits the amount of RAM occupied. It
> doesn't stop the memory from being swapped out. You need to limit swap
> memory, too. Take note that swap accounting may have noticeable
> overheads and as such is not enabled by default on many systems.
> 
By this reason, MemorySwapMax= option is introduced.

https://github.com/systemd/systemd/pull/3659

Note, MemorySwapLimit= does not exist. Lennard does not want to add more
options for legacy cgroup. Further, the swap limit operations different
between legacy and unified cgroup. So adding MemorySwapLimit= was not
good idea.

> 
>> htop shows a memory consumption of 1.4 GB. The output of
>> `systemd-cgtop` is:
>>
>> Control Group Tasks   %CPU   Memory
>> Input/s Output/s
>> / -1.5
>> 1.7G-
>>
>> /user.slice  460.4
>> 14.3M-
>>
>> /user.slice/user-1001.slice  460.4
>> 14.2M-
>>
>> /init.scope   1  -
>> 1.4M-
>>
>> /system.slice
>>
>>
>> So my question is how would MemoryLimit= work for a user unit?
> 
> Maybe you want to apply the limit to a slice? Your output of cgtop
> doesn't show any service units...
> 
> 
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Re: [systemd-devel] MemoryLimit for user unit

[Kai Krakow]

Am Sun, 12 Nov 2017 18:14:38 +0100
schrieb Stefan Schweter :

> Hi systemd-users,
> 
> I tried to add a memory limit for a user service unit (inspired by
> [1]), it looks like:
> 
> [Service]
> # 
> MemoryAccounting=true
> MemoryLimit=1G
> 
> Now the problem is that the (user) service consumes more than 1G
> without being terminated.

As far as I could see, this limits the amount of RAM occupied. It
doesn't stop the memory from being swapped out. You need to limit swap
memory, too. Take note that swap accounting may have noticeable
overheads and as such is not enabled by default on many systems.


> htop shows a memory consumption of 1.4 GB. The output of
> `systemd-cgtop` is:
> 
> Control Group Tasks   %CPU   Memory
> Input/s Output/s
> / -1.5
> 1.7G-
> 
> /user.slice  460.4
> 14.3M-
> 
> /user.slice/user-1001.slice  460.4
> 14.2M-
> 
> /init.scope   1  -
> 1.4M-
> 
> /system.slice
> 
> 
> So my question is how would MemoryLimit= work for a user unit?

Maybe you want to apply the limit to a slice? Your output of cgtop
doesn't show any service units...


-- 
Regards,
Kai

Replies to list-only preferred.

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[systemd-devel] MemoryLimit for user unit

[Stefan Schweter]

Hi systemd-users,

I tried to add a memory limit for a user service unit (inspired by [1]),
it looks like:

[Service]
# 
MemoryAccounting=true
MemoryLimit=1G

Now the problem is that the (user) service consumes more than 1G without
being terminated.

htop shows a memory consumption of 1.4 GB. The output of `systemd-cgtop` is:

Control Group Tasks   %CPU   Memory  Input/s
Output/s
/ -1.5 1.7G-

/user.slice  460.414.3M-

/user.slice/user-1001.slice  460.414.2M-

/init.scope   1  - 1.4M-

/system.slice


So my question is how would MemoryLimit= work for a user unit?

My system is Debian 9 with systemd:

$ systemctl --version
systemd 232
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP
+LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS
+KMOD +IDN


Thanks in advance + regards.

Stefan

[1] http://0pointer.de/blog/projects/resources.html
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