Re: [linux-lvm] system boot time regression when using lvm2-2.03.05

[Martin Wilck <mwilck@suse.de>]

On Wed, 2019-09-11 at 11:13 +0200, Zdenek Kabelac wrote:
> Dne 11. 09. 19 v 9:17 Martin Wilck napsal(a):
> > 
> > My idea was not to skip synchronization entirely, but to consider
> > moving it to a separate process / service. I surely don't want to
> > re-
> > invent lvmetad, but Heming's findings show that it's more efficient
> > to
> > do activation in a "single swoop" (like lvm2-activation.service)
> > than
> > with many concurrent pvscan processes.
> > 
> > So instead of activating a VG immediately when it sees all
> > necessary
> > PVs are detected, pvscan could simply spawn a new service which
> > would
> > then take care of the activation, and sync with udev.
> > 
> > Just a thought, I lack in-depth knowledge of LVM2 internals to know
> > if
> > it's possible.
> 
> Well for relatively long time we do want to move 'pvscan' back to be
> processed 
> within udev rules  and activation service being really just a service
> doing  'vgchange -ay'.

That sounds promising (I believe pvscan could well still be called via
'ENV{SYSTEMD_WANTS}+=' rather than being directly called from udev
rules, but that's just a detail). 
But it doesn't sound as if such a solution was imminent, right?

> Another floating idea is to move towards monitoring instead of using
> semaphore
> (since those SysV resources are kind-of limited and a bit problematic
> when there are left in the system).

I'm not sure I understand - are you talking about udev monitoring?

Thanks
Martin