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

Zdenek Kabelac zkabelac at redhat.com
Mon Jun 7 16:31:13 UTC 2021

Dne 07. 06. 21 v 17:48 Martin Wilck napsal(a):
> On So, 2021-06-06 at 14:15 +0800, heming.zhao at suse.com wrote:
>> 1. During boot phase, lvm2 automatically swithes to direct activation
>> mode
>> ("event_activation = 0"). After booted, switch back to the event
>> activation mode.
>> Booting phase is a speical stage. *During boot*, we could "pretend"
>> that direct
>> activation (event_activation=0) is set, and rely on lvm2-activation-
>> *.service
>> for PV detection. Once lvm2-activation-net.service has finished, we
>> could
>> "switch on" event activation.
> I like this idea. Alternatively, we could discuss disabling event
> activation only in the "coldplug" phase after switching root (i.e.
> between start of systemd-udev-trigger.service and lvm2-
> activation.service), because that's the critical time span during which
> 1000s of events can happen simultaneously.


In lvm2 we never actually suggested to use 'autoactivation' during the boot - 
this case doesn't make much sense - as it's already know ahead of time which 
device ID is needed to be activated. So whoever started to use autoactivation 
during boot - did it his own distro way.   Fedora  nor RHEL uses this.  On 
second note  David is currently trying to optimize and rework Dracut's booting 
as it didn't aged quite well and there are several weak points to be fixed.



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