[linux-lvm] Discussion: performance issue on event activation mode

[David Teigland]

On Wed, Oct 20, 2021 at 02:54:54PM +0000, Martin Wilck wrote:
> I see. The problem with IMPORT (like RUN, actually) is that it's
> required to finish quickly, which might not be the case if we encounter
> resource shortage / contention as observed by Heming. If that happens,
> the programs started may be killed by udevd, with unpredictable
> results.

We've been optimizing the pvscan --cache command that gets the VG name
from the disk and checks if the VG is complete.  It's pretty small and
fast at this point.  Also, the lvm-activate-vgs services that we have been
discussing should result in a large number of those pvscans doing nothing
(i.e. those that are triggered prior to lvm-activate-vgs-last.service will
see that event-based activation is not yet enabled and will exit.)

Dave