When doing CPU or memory hotplug, multiple udev events will be triggered together. This will bring unnecessary workload for the host and make udev take much longer to settle.

Previous commit f2883275 added a workaround to solve the problem of systemd failing kdump servive due to burst of restart requests, but the unnecessary workload is not reduced. And currently, this is causing timeout failure on Hyper-V environment.

This patch fixes the problem by merging concurrent kdump restart requests. Tested with Hyper-V VM, no new issues found.

Signed-off-by: Kairui Song kasong@redhat.com --- 98-kexec.rules | 8 ++++---- kdump-udev-throttler | 25 +++++++++++++++++++++++++ kexec-tools.spec | 2 ++ 3 files changed, 31 insertions(+), 4 deletions(-) create mode 100755 kdump-udev-throttler

diff --git a/98-kexec.rules b/98-kexec.rules index e32ee13..eee1df1 100644 --- a/98-kexec.rules +++ b/98-kexec.rules @@ -1,4 +1,4 @@ -SUBSYSTEM=="cpu", ACTION=="add", PROGRAM="/bin/systemctl try-restart kdump.service" -SUBSYSTEM=="cpu", ACTION=="remove", PROGRAM="/bin/systemctl try-restart kdump.service" -SUBSYSTEM=="memory", ACTION=="online", PROGRAM="/bin/systemctl try-restart kdump.service" -SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="/bin/systemctl try-restart kdump.service" +SUBSYSTEM=="cpu", ACTION=="add", PROGRAM="kdump-udev-throttler" +SUBSYSTEM=="cpu", ACTION=="remove", PROGRAM="kdump-udev-throttler" +SUBSYSTEM=="memory", ACTION=="online", PROGRAM="kdump-udev-throttler" +SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="kdump-udev-throttler" diff --git a/kdump-udev-throttler b/kdump-udev-throttler new file mode 100755 index 0000000..272d226 --- /dev/null +++ b/kdump-udev-throttler @@ -0,0 +1,25 @@ +#!/bin/bash + +throttle_lock="/var/lock/kdump-udev-throttle" +interval=2 + +exec 9>$throttle_lock +flock -n 9 + +if [ $? -ne 0 ]; then + echo "Another app is currently holding the throttle lock, extend throttle timing and exiting" + exit 0 +fi + +timeout_time() { + echo $(($(stat -c "%Y" $throttle_lock) + $interval)) +} + +# Wait until no one try to acquire the throttle_lock in past $interval seconds +while [[ $(timeout_time) -gt $(date +%s) ]]; do + sleep 1 +done + +systemctl try-restart kdump + +exit 0 diff --git a/kexec-tools.spec b/kexec-tools.spec index 6330534..fedce60 100644 --- a/kexec-tools.spec +++ b/kexec-tools.spec @@ -29,6 +29,7 @@ Source24: kdump.sysconfig.ppc64le Source25: kdumpctl.8 Source26: live-image-kdump-howto.txt Source27: early-kdump-howto.txt +Source28: kdump-udev-throttler

####################################### # These are sources for mkdumpramfs @@ -171,6 +172,7 @@ install -m 755 %{SOURCE23} $RPM_BUILD_ROOT%{_prefix}/lib/kdump/kdump-lib-initram # For s390x the ELF header is created in the kdump kernel and therefore kexec # udev rules are not required install -m 644 %{SOURCE14} $RPM_BUILD_ROOT%{_udevrulesdir}/98-kexec.rules +install -m 644 %{SOURCE28} $RPM_BUILD_ROOT%{_udevrulesdir}/../kdump-udev-throttler %endif install -m 644 %{SOURCE15} $RPM_BUILD_ROOT%{_mandir}/man5/kdump.conf.5 install -m 644 %{SOURCE16} $RPM_BUILD_ROOT%{_unitdir}/kdump.service