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43 lines
1.4 KiB
43 lines
1.4 KiB
3 years ago
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#!/bin/bash
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# This util helps to reduce the workload of kdump service restarting
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# on udev event. When hotplugging memory / CPU, multiple udev
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# events may be triggered concurrently, and obviously, we don't want
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# to restart kdump service for each event.
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# This script will be called by udev, and make sure kdump service is
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# restart after all events we are watching are settled.
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# On each call, this script will update try to aquire the $throttle_lock
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# The first instance acquired the file lock will keep waiting for events
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# to settle and then reload kdump. Other instances will just exit
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# In this way, we can make sure kdump service is restarted immediately
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# and for exactly once after udev events are settled.
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throttle_lock="/var/lock/kdump-udev-throttle"
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exec 9>$throttle_lock
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if [ $? -ne 0 ]; then
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echo "Failed to create the lock file! Fallback to non-throttled kdump service restart"
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/bin/kdumpctl reload
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exit 1
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fi
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flock -n 9
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if [ $? -ne 0 ]; then
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echo "Throttling kdump restart for concurrent udev event"
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exit 0
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fi
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# Wait for at least 1 second, at most 4 seconds for udev to settle
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# Idealy we will have a less than 1 second lag between udev events settle
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# and kdump reload
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sleep 1 && udevadm settle --timeout 3
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# Release the lock, /bin/kdumpctl will block and make the process
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# holding two locks at the same time and we might miss some events
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exec 9>&-
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/bin/kdumpctl reload
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exit 0
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