[PATCH 0/3] mdev: add daemon mode

[Laurent Bercot]

>If mdev is used as kernel hotplug helper and the system generates many
>hotplug events it will quickly consume considerable resources because a
>process is forked for each event and, if the mdev.seq feature is used,
>they must also coordinate among each other. While the uevent applet
>mitigates some of the resource problems you still have to pay the cost
>for a fork/exec and parsing of mdev.conf for each event.

  Doing it that way spares the fork/exec indeed, but you're still
parsing mdev.conf for every event. The parsing is done in
make_device(), which is called at least once per event. And there's
no way to prevent that - that's just how mdev is structured.
To parse mdev.conf only once and have a really fast code path on
event reception, you'd basically need to rewrite mdev entirely.

  Are you aware of https://skarnet.org/software/mdevd/ ? :)

--
  Laurent
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