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module/cgroups: robustify task freezer

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The set() method of the CGroup class used to freeze tasks relies on
target's write_value(). Sometimes, the freezing procedure takes some
time and the call to write_value() in set() fails by reading "FREEZING"
while it expected "FROZEN". To avoid this issue, this commits introduces
a shutil call dedicated to changing the state of the freezer controller.
This commit is contained in:
Quentin Perret 2017-08-21 18:16:10 +01:00
parent 66a50a2f49
commit 4b36439de8
2 changed files with 23 additions and 3 deletions
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20
devlib/bin/scripts/shutils.in
View File

@ -177,6 +177,23 @@ cgroups_tasks_in() {
exit 0
}
cgroups_freezer_set_state() {
STATE=${1}
SYSFS_ENTRY=${2}/freezer.state
# Set the state of the freezer
echo $STATE > $SYSFS_ENTRY
# And check it applied cleanly
for i in `seq 1 10`; do
[ $($CAT $SYSFS_ENTRY) = $STATE ] && exit 0
sleep 1
done
# We have an issue
echo "ERROR: Freezer stalled while changing state to \"$STATE\"." >&2
exit 1
}
################################################################################
# Main Function Dispatcher
@ -213,6 +230,9 @@ cgroups_tasks_move)
cgroups_tasks_in)
cgroups_tasks_in $*
;;
cgroups_freezer_set_state)
cgroups_freezer_set_state $*
;;
ftrace_get_function_stats)
ftrace_get_function_stats
;;

6
devlib/module/cgroups.py
View File

@ -466,11 +466,11 @@ class CgroupsModule(Module):
if freezer is None:
raise RuntimeError('freezer cgroup controller not present')
freezer_cg = freezer.cgroup('/DEVLIB_FREEZER')
thawed_cg = freezer.cgroup('/')
cmd = 'cgroups_freezer_set_state {{}} {}'.format(freezer_cg.directory)
if thaw:
# Restart froozen tasks
freezer_cg.set(state='THAWED')
freezer.target._execute_util(cmd.format('THAWED'), as_root=True)
# Remove all tasks from freezer
freezer.move_all_tasks_to('/')
return
@ -482,7 +482,7 @@ class CgroupsModule(Module):
tasks = freezer.tasks('/')
# Freeze all tasks
freezer_cg.set(state='FROZEN')
freezer.target._execute_util(cmd.format('FROZEN'), as_root=True)
return tasks