On Sat, 3 Jul 2021 at 05:17, David Teigland <teigland@xxxxxxxxxx> wrote: > > On Sun, Jun 06, 2021 at 02:15:23PM +0800, heming.zhao@xxxxxxxx wrote: > > dev_cache_scan //order: O(n^2) > > + _insert_dirs //O(n) > > | if obtain_device_list_from_udev() true > > | _insert_udev_dir //O(n) > > | > > + dev_cache_index_devs //O(n) > > I've been running some experiments and trying some patches to improve > this. By setting obtain_device_list_from_udev=0, and using the attached > patch to disable dev_cache_index_devs, the pvscan is much better. > > systemctl status lvm2-pvscan appears to show that the pvscan command > itself runs for only 2-4 seconds, while the service as a whole takes > around 15 seconds. See the 16 sec gap below from the end of pvscan > to the systemd Started message. If that's accurate, the remaining delay > would lie outside lvm. Not necessarily. It could be pvscan stalling for 16s after printing the "now active" message for some reason before exiting (with 0). > > Jul 02 15:27:57 localhost.localdomain systemd[1]: Starting LVM event activation on device 253:1710... > Jul 02 15:28:00 localhost.localdomain lvm[65620]: pvscan[65620] PV /dev/mapper/mpathalz online, VG 1ed02c7d-0019-43c4-91b5-f220f3521ba9 is complete. > Jul 02 15:28:00 localhost.localdomain lvm[65620]: pvscan[65620] VG 1ed02c7d-0019-43c4-91b5-f220f3521ba9 run autoactivation. > Jul 02 15:28:00 localhost.localdomain lvm[65620]: 1 logical volume(s) in volume group "1ed02c7d-0019-43c4-91b5-f220f3521ba9" now active > Jul 02 15:28:16 localhost.localdomain systemd[1]: Started LVM event activation on device 253:1710. > > _______________________________________________ > 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/ _______________________________________________ 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/
