On 10/18/21 23:04, David Teigland wrote:
On Mon, Oct 18, 2021 at 06:24:49AM +0000, Martin Wilck wrote:I'd like to second Peter here, "RUN" is in general less fragile than "IMPORT{PROGRAM}". You should use IMPORT{PROGRAM}" if and only if - the invoked program can work with incomplete udev state of a device (the progrem should not try to access the device via libudev, it should rather get properties either from sysfs or the uevent's environment variables) - you need the result or the output of the program in order to proceed with rules processing.Those are both true in this case. I can't say I like it either, but udev rules force hacky solutions on us. I began trying to use RUN several months ago and I think I gave up trying to find a way to pass values from the RUN program back into the udev rule (possibly by writing values to a temp file and then doing IMPORT{file}). The udev rule needs the name of the VG to activate, and that name comes from the pvscan. For an even uglier form of this, see the equivalent I wrote for dracut: https://github.com/dracutdevs/dracut/pull/1567/files The latest version of the hybrid service+event activation is here https://sourceware.org/git/?p=lvm2.git;a=shortlog;h=refs/heads/dev-dct-activation-switch-7 I've made it simple to edit lvm.conf to switch between: - activation from fixed services only - activation from events only - activation from fixes services first, then from events
For the branch code of dev-dct-activation-switch-7, If the comment before event_activation_enable() is correct. option "event_activation" becomes useless. I still prefer to use one switcher to control all behaviors.
There are sure to be tradeoffs, we know that many concurrent activations from events are slow, and fixed services which are more serialized could be delayed from slow devices. I'm still undecided on the best default setting, i.e. which will work best for most people, and would welcome any thoughts or relevant experience.
from my test results, I never meet delay issue under serialized mode (except udev.children_max=1). I prefer to set services first, then events. This style will triggers performance issue after entering events mode, but this is under expectation. Thanks, Heming _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
