[systemd-devel] 11 MB cost of DefaultMemoryAccounting=yes

[Kai Krakow]

Am Thu, 11 May 2017 10:26:33 +0200
schrieb Umut Tezduyar Lindskog <umut at tezduyar.com>:

> Hello,
> 
> Even though this is not a systemd problem, I believe systemd mailing
> list is a good place to discuss.
> 
> Our kernel has CONFIG_MEMCG enabled. As soon as we set
> DefaultMemoryAccounting=yes, our system wide memory usage increased 11
> MB. The increase is mostly on kmalloc-* slab memory with the peak on
> kmalloc-32.
> 
> I initially thought the increase is due to systemd creating
> system.slice under /sys/fs/cgroup/memory but I think I am wrong. I
> have run "systemd-run -p MemoryLimit=10M /bin/sleep 5" command while
> DefaultMemoryAccounting=no and there was no significant memory usage.
> 
> I am quite puzzled about where this extra cost is coming from. Does
> anybody have any idea?

I think this is documented in the kernel as far as I know: Memory
accounting needs some extra memory. For swap accounting, it is even
more.

If you look at the kernel documentation: Does this explain your issue?

-- 
Regards,
Kai

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