Previously, kdump will restart / reload for many times on hotplug
event, especially memory hotplug events. Hotplugged memory may
generate many udev event as memory are managed and hotplugged in
small chunks by the kernel.
This results in unnecessary system workload and an actually longer
delay of kdump reload and the hotplug event, as udev will either
get blocked or kdumpctl will be waiting for other triggered operation.
To fix this, introduce a kdump-udev-throttler as an agent which will
be called by udev and merge concurrent kdump restart requests. Tested
with a Hyper-V VM which is failing due to udev timeout previously,
no new issues found.
Signed-off-by: Kairui Song <kasong@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
