From 4daf99fc2cb6d873e804d24d56ddd849fc4e514b Mon Sep 17 00:00:00 2001
From: Adriaan Schmidt <adriaan.schmidt@siemens.com>
Date: Wed, 10 Aug 2022 05:05:03 +0000
Subject: [PATCH] feat(scheduler): match thread names in addition to process
 names

This is a first try at matching thread names (comm) in addition to
the process cmdline for changing scheduling policies and priorities
with the `scheduler` plugin.

It adds an optional second regex field to the end of `group.*`
options (defaults to ".*"). The first regex is to match the
process cmdline, the second one is used to match the thread's
comm. If both match, scheduling options are applied.

Note that you can have multiple `group.*` options with the
same process regex and different thread regexes. You can even have
one rule to match a specific thread name, and another with no thread
regex (matching all threads). In this case you need to assign rule
priorities (higher number -> higher priority).

Signed-off-by: Adriaan Schmidt <adriaan.schmidt@siemens.com>
---
 profiles/realtime-virtual-guest/tuned.conf |  2 +-
 profiles/realtime-virtual-host/tuned.conf  |  2 +-
 tuned/plugins/plugin_scheduler.py          | 67 ++++++++++++++++------
 3 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/profiles/realtime-virtual-guest/tuned.conf b/profiles/realtime-virtual-guest/tuned.conf
index a381f41..288f9d0 100644
--- a/profiles/realtime-virtual-guest/tuned.conf
+++ b/profiles/realtime-virtual-guest/tuned.conf
@@ -22,7 +22,7 @@ non_isolated_cores=${f:cpulist_invert:${isolated_cores}}
 assert2=${f:assertion:isolated_cores contains online CPU(s):${isolated_cores_expanded}:${isolated_cores_online_expanded}}
 
 [scheduler]
-# group.group_name=rule_priority:scheduler_policy:scheduler_priority:core_affinity_in_hex:process_name_regex
+# group.group_name=rule_priority:scheduler_policy:scheduler_priority:core_affinity_in_hex:process_name_regex[:thread_name_regex]
 # for i in `pgrep ksoftirqd` ; do grep Cpus_allowed_list /proc/$i/status ; done
 group.ksoftirqd=0:f:2:*:^\[ksoftirqd
 group.ktimers=0:f:2:*:^\[ktimers
diff --git a/profiles/realtime-virtual-host/tuned.conf b/profiles/realtime-virtual-host/tuned.conf
index b0e8846..0f520df 100644
--- a/profiles/realtime-virtual-host/tuned.conf
+++ b/profiles/realtime-virtual-host/tuned.conf
@@ -27,7 +27,7 @@ non_isolated_cores=${f:cpulist_invert:${isolated_cores}}
 assert2=${f:assertion:isolated_cores contains online CPU(s):${isolated_cores_expanded}:${isolated_cores_online_expanded}}
 
 [scheduler]
-# group.group_name=rule_priority:scheduler_policy:scheduler_priority:core_affinity_in_hex:process_name_regex
+# group.group_name=rule_priority:scheduler_policy:scheduler_priority:core_affinity_in_hex:process_name_regex[:thread_name_regex]
 # for i in `pgrep ksoftirqd` ; do grep Cpus_allowed_list /proc/$i/status ; done
 group.ksoftirqd=0:f:2:*:^\[ksoftirqd
 group.ktimers=0:f:2:*:^\[ktimers
diff --git a/tuned/plugins/plugin_scheduler.py b/tuned/plugins/plugin_scheduler.py
index 10ff4e7..74678d9 100644
--- a/tuned/plugins/plugin_scheduler.py
+++ b/tuned/plugins/plugin_scheduler.py
@@ -565,10 +565,11 @@ class SchedulerPlugin(base.Plugin):
 		if not isinstance(process, procfs.process):
 			pid = process
 			process = procfs.process(pid)
-		cmdline = procfs.process_cmdline(process)
+		cmd = procfs.process_cmdline(process)
+		comm = process['stat']['comm']
 		if self._is_kthread(process):
-			cmdline = "[" + cmdline + "]"
-		return cmdline
+			return "[" + cmd + "]", "[" + comm + "]"
+		return cmd, comm
 
 	# Raises OSError, IOError
 	def get_processes(self):
@@ -582,7 +583,7 @@ class SchedulerPlugin(base.Plugin):
 				processes[pid] = cmd
 				if "threads" in proc:
 					for pid in proc["threads"].keys():
-						cmd = self._get_cmdline(proc)
+						cmd = self._get_cmdline(pid)
 						processes[pid] = cmd
 			except (OSError, IOError) as e:
 				if e.errno == errno.ENOENT \
@@ -817,7 +818,16 @@ class SchedulerPlugin(base.Plugin):
 		(scheduler, priority) = self._convert_sched_params(
 				scheduler, priority)
 		affinity = self._convert_affinity(affinity)
-		return (rule_prio, scheduler, priority, affinity, regex)
+		# split regex into two, one to match the cmdline, and one the comm
+		# if there is only one regex for the cmdline, then the comm is matched by ".*"
+		# allow escaping of colons in regexes (-> '\:' is not a delimiter in the split)
+		regexes = re.split(r'(?<!\\):', regex, 1)
+		r1 = regexes[0].replace(r'\:', ':')
+		try:
+			r2 = regexes[1].replace(r'\:', ':')
+		except IndexError:
+			r2 = ".*"
+		return (rule_prio, scheduler, priority, affinity, r1, r2)
 
 	def _cgroup_create_group(self, cgroup):
 		path = "%s/%s" % (self._cgroup_mount_point, cgroup)
@@ -934,24 +944,34 @@ class SchedulerPlugin(base.Plugin):
 		sched_cfg = sorted(buf, key=lambda option_vals: option_vals[1][0])
 		sched_all = dict()
 		# for runtime tuning
+		# _sched_lookup is a dict mapping a cmdline regex to a list of scheduling
+		# parameters, each with a secondary regex to match the comm, sorted from lowest
+		# to highest priority
 		instance._sched_lookup = {}
-		for option, (rule_prio, scheduler, priority, affinity, regex) \
+		for option, (rule_prio, scheduler, priority, affinity, regex, regex2) \
 				in sched_cfg:
 			try:
-				r = re.compile(regex)
+				r1 = re.compile(regex)
 			except re.error as e:
 				log.error("error compiling regular expression: '%s'" % str(regex))
 				continue
-			processes = [(pid, cmd) for pid, cmd in ps.items() if re.search(r, cmd) is not None]
+			try:
+				r2 = re.compile(regex2)
+			except re.error as e:
+				log.error("error compiling regular expression: '%s'" % str(regex2))
+				continue
+			processes = [(pid, cmd) for pid, cmd in ps.items() if re.search(r1, cmd[0]) is not None and re.search(r2, cmd[1]) is not None]
 			#cmd - process name, option - group name
-			sched = dict([(pid, (cmd, option, scheduler, priority, affinity, regex))
+			sched = dict([(pid, (cmd, option, scheduler, priority, affinity))
 					for pid, cmd in processes])
 			sched_all.update(sched)
 			# make any contained regexes non-capturing: replace "(" with "(?:",
 			# unless the "(" is preceded by "\" or followed by "?"
 			regex = re.sub(r"(?<!\\)\((?!\?)", "(?:", str(regex))
-			instance._sched_lookup[regex] = [scheduler, priority, affinity]
-		for pid, (cmd, option, scheduler, priority, affinity, regex) \
+			if not regex in instance._sched_lookup:
+				instance._sched_lookup[regex] = []
+			instance._sched_lookup[regex].append([scheduler, priority, affinity, r2])
+		for pid, (cmd, option, scheduler, priority, affinity) \
 				in sched_all.items():
 			self._tune_process(pid, cmd, scheduler,
 					priority, affinity)
@@ -1060,14 +1080,23 @@ class SchedulerPlugin(base.Plugin):
 				log.error("Failed to get cmdline of PID %d: %s"
 						% (pid, e))
 			return
-		v = self._cmd.re_lookup(instance._sched_lookup, cmd, r)
-		if v is not None and not pid in self._scheduler_original:
-			log.debug("tuning new process '%s' with PID '%d' by '%s'" % (cmd, pid, str(v)))
-			(sched, prio, affinity) = v
-			self._tune_process(pid, cmd, sched, prio,
-					affinity)
-			self._storage.set(self._scheduler_storage_key,
-					self._scheduler_original)
+		# first match against cmdline, uses the optimized re_lookup
+		vs = self._cmd.re_lookup(instance._sched_lookup, cmd[0], r)
+		if vs is not None and not pid in self._scheduler_original:
+			tune_v = None
+			# second match against comm, reversed to start with the highest priority
+			for v in reversed(vs):
+				if re.search(v[3], cmd[1]) is not None:
+					tune_v = v[:3]
+					break
+
+			if tune_v is not None:
+				log.debug("tuning new process '%s' with PID '%d' by '%s'" % (cmd, pid, str(tune_v)))
+				(sched, prio, affinity) = tune_v
+				self._tune_process(pid, cmd, sched, prio,
+						affinity)
+				self._storage.set(self._scheduler_storage_key,
+						self._scheduler_original)
 
 	def _remove_pid(self, instance, pid):
 		if pid in self._scheduler_original: