Merge pull request #453 from yarda/builtin_function_calc_isolated_cores

builtin functions: added calc_isolated_cores function

profiles/cpu-partitioning/cpu-partitioning-variables.conf

@@ -2,5 +2,8 @@
 # isolated_cores=2,4-7
 # isolated_cores=2-23
 #
+# Reserve 1 core per socket for housekeeping, isolate the rest.
+isolated_cores=${f:calc_isolated_cores:1}
+
 # To disable the kernel load balancing in certain isolated CPUs:
 # no_balance_cores=5-10

profiles/realtime-virtual-guest/realtime-virtual-guest-variables.conf

@@ -6,6 +6,9 @@
 # isolated_cores=2,4-7
 # isolated_cores=2-23
 #
+# Reserve 1 core per socket for housekeeping, isolate the rest.
+isolated_cores=${f:calc_isolated_cores:1}
+
 #
 # Uncomment the 'isolate_managed_irq=Y' bellow if you want to move kernel
 # managed IRQs out of isolated cores. Note that this requires kernel

profiles/realtime-virtual-host/realtime-virtual-host-variables.conf

@@ -6,7 +6,9 @@
 # isolated_cores=2,4-7
 # isolated_cores=2-23
 #
-#
+# Reserve 1 core per socket for housekeeping, isolate the rest.
+isolated_cores=${f:calc_isolated_cores:1}
+
 # Uncomment the 'isolate_managed_irq=Y' bellow if you want to move kernel
 # managed IRQs out of isolated cores. Note that this requires kernel
 # support. Please only specify this parameter if you are sure that the

profiles/realtime/realtime-variables.conf

@@ -2,6 +2,9 @@
 # isolated_cores=2,4-7
 # isolated_cores=2-23
 #
+# Reserve 1 core per socket for housekeeping, isolate the rest.
+isolated_cores=${f:calc_isolated_cores:1}
+
 #
 # Uncomment the 'isolate_managed_irq=Y' bellow if you want to move kernel
 # managed IRQs out of isolated cores. Note that this requires kernel

tuned/consts.py

@@ -66,6 +66,9 @@ SYSTEMD_CPUAFFINITY_VAR = "CPUAffinity"
 # irqbalance plugin configuration
 IRQBALANCE_SYSCONFIG_FILE = "/etc/sysconfig/irqbalance"
 
+# built-in functions configuration
+SYSFS_CPUS_PATH = "/sys/devices/system/cpu"
+
 # number of backups
 LOG_FILE_COUNT = 2
 LOG_FILE_MAXBYTES = 100*1000

tuned/profiles/functions/function_calc_isolated_cores.py

@@ -0,0 +1,44 @@
+import os
+import glob
+import tuned.logs
+from . import base
+import tuned.consts as consts
+
+log = tuned.logs.get()
+
+class calc_isolated_cores(base.Function):
+	"""
+	Calculates and returns isolated cores. The argument specifies how many
+	cores per socket reserve for housekeeping. If not specified, 1 core
+	per socket is reserved for housekeeping and the rest is isolated.
+	"""
+	def __init__(self):
+		# max 1 argument
+		super(calc_isolated_cores, self).__init__("calc_isolated_cores", 1)
+
+	def execute(self, args):
+		if not super(calc_isolated_cores, self).execute(args):
+			return None
+		cpus_reserve = 1
+		if len(args) > 0:
+			if not args[0].isdecimal() or int(args[0]) < 0:
+				log.error("invalid argument '%s' for builtin function '%s', it must be non-negative integer" %
+					(args[0], self._name))
+				return None
+			else:
+				cpus_reserve = int(args[0])
+
+		topo = {}
+		for cpu in glob.iglob(os.path.join(consts.SYSFS_CPUS_PATH, "cpu*")):
+			cpuid = os.path.basename(cpu)[3:]
+			if cpuid.isdecimal():
+				socket = self._cmd.read_file(os.path.join(cpu, "topology/physical_package_id")).strip()
+				if socket.isdecimal():
+					topo[socket] = topo.get(socket, []) + [cpuid]
+
+		isol_cpus = []
+		for cpus in topo.values():
+			cpus.sort(key = int)
+			isol_cpus = isol_cpus + cpus[cpus_reserve:]
+		isol_cpus.sort(key = int)
+		return ",".join(isol_cpus)