[systemd-devel] minimum space needed for reload/reexec

[CHEN, Jack]

Hi,

I happen to see to a fix in system, which adds a space checking before reload/reexec.
>From the code:
Require 16MiB free in /run/systemd for reloading/reexecing. After all we need to serialize our state there, and if
* we can't we'll fail badly
#define RELOAD_DISK_SPACE_MIN (UINT64_C(16) * UINT64_C(1024) * UINT64_C(1024))
And I got further explanation from poettering:
it's a "safety buffer", see commit msg of the fix. It's set to 16M because it has to be set to something, and it sounded like a reasonably value, and so far we got no feedback to the contrary

However, just for “serialize our state there”, literally, there is no need for such a big space (16M).
There is no problem for PC. But for embedded devices, 16M is quite prodigal.
And in my test, even 1M free space would allow reloading/reexecing to work normally.

Shall we remove this restriction? (Removing I mean we just check if there is free space or not) Or at least lower the threshold.
It is not good to forbid reloading/reexecing when there is enough free space, just because it is smaller than the threshold (16M)。

Best Regards
Zenghu Chen
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