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scheduler: Postpone cgroup blacklist check and double-check after fail

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It may happen that a process gets moved into a blacklisted cgroup
when TuneD is already applying a profile. Postpone the filtering of
processes according to the blacklist to the last possible moment to
minimize the race window.

When setting process affinity fails, re-check whether the process
belongs to a blacklisted cgroup once again and do not report an
error if that's the case.

Resolves: RHEL-72981
This commit is contained in:
Pavol Žáčik 2025-01-15 15:57:13 +01:00
parent 55e272e263
commit 7113c91b5b
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GPG key ID: B99527D5E6487A92
1 changed files with 16 additions and 6 deletions
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22
tuned/plugins/plugin_scheduler.py
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@ -644,15 +644,24 @@ class SchedulerPlugin(base.Plugin):
def _is_kthread(self, process):
return process["stat"]["flags"] & procfs.pidstat.PF_KTHREAD != 0
def _process_in_blacklisted_cgroup(self, process):
if self._cgroup_ps_blacklist_re == "":
return False
return re.search(self._cgroup_ps_blacklist_re, self._get_stat_cgroup(process)) is not None
# Returns True if we can ignore a failed affinity change of
# a process with the given PID and therefore not report it as an error.
def _ignore_set_affinity_error(self, pid):
def _ignore_set_affinity_error(self, process):
pid = process.pid
try:
process = procfs.process(pid)
if process["stat"]["state"] == "Z":
log.debug("Affinity of zombie task with PID %d could not be changed."
% pid)
return True
if self._process_in_blacklisted_cgroup(process):
log.debug("Affinity of task with PID %d could not be changed, the task was moved into a blacklisted cgroup."
% pid)
return True
if process["stat"].is_bound_to_cpu():
if self._is_kthread(process):
log.debug("Affinity of kernel thread with PID %d cannot be changed, the task's affinity mask is fixed."
@ -1168,13 +1177,17 @@ class SchedulerPlugin(base.Plugin):
return res
def _set_affinity(self, pid, affinity):
process = procfs.process(pid)
if self._process_in_blacklisted_cgroup(process):
log.debug("Not setting CPU affinity of PID %d, the task belongs to a blacklisted cgroup." % pid)
return
log.debug("Setting CPU affinity of PID %d to '%s'." % (pid, affinity))
try:
self._scheduler_utils.set_affinity(pid, affinity)
# Workaround for old python-schedutils (pre-0.4) which
# incorrectly raised SystemError instead of OSError
except (SystemError, OSError) as e:
if not self._ignore_set_affinity_error(pid):
if not self._ignore_set_affinity_error(process):
log.error("Failed to set affinity of PID %d to '%s': %s"
% (pid, affinity, e))
@ -1191,9 +1204,6 @@ class SchedulerPlugin(base.Plugin):
if self._ps_blacklist != "":
psl = [v for v in psl if re.search(self._ps_blacklist,
self._get_stat_comm(v)) is None]
if self._cgroup_ps_blacklist_re != "":
psl = [v for v in psl if re.search(self._cgroup_ps_blacklist_re,
self._get_stat_cgroup(v)) is None]
psd = dict([(v.pid, v) for v in psl])
for pid in psd:
try: