[systemd-devel] Antw: [EXT] Re: Memory in systemctl status

[Ulrich Windl]

>>> Reindl Harald <h.reindl at thelounge.net> schrieb am 28.09.2020 um 10:08 in
Nachricht <5b087cb0-9588-56db-1955-522ac9a6b701 at thelounge.net>:

> 
> Am 27.09.20 um 23:39 schrieb Benjamin Berg:
>>>>> however, that value makes little to no sense and if that's the same
>>>>> value as accounted for "MemoryMax" it's plain wrong
>> But it does make sense. File caches are part of the working set of
>> memory that a process needs. Setting MemoryMax=/MemoryMin=
>> limits/guarantees the size of this working set. These kinds of limits
>> or protections would be a lot less meaningful if caches were not
>> accounted for.
> 
> sorry but that is complete nosense
> 
> caches are freed as soon whatever process asks for RAM and so they are
> *not* part of the working set
> 
> that kind of limits are completly useless when i would limit a service
> to 4 GB but because it served a few million different files within the
> last weeks which are accounted to it's cache and working set it's now
> killed?

Actually there are valid reasons to limit the amount of cache a process may
allocate. For example when a process creates a lot of dirty buffers quickly
(e.g. writing to a slow disk), it may cause a read-stall for the whole system.

> 
> my webserver is killed because it served at monday, tuesday, thursday
> and friday 4 different files with 2 GB?

cgroups is for limiting resources, not for killing processes AFAIK.

> 
> frankly my webserver can't even do anything against caching of teh VFS
> layer and is not responsible at all nor do other services
> 
> BTW: stop "reply‑all" to mailing‑lists
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