[v4,1/3] tuna: Add functionality to set the cstate of specified CPUs when running tuna

diff --git a/tuna-cmd.py b/tuna-cmd.py
index f37e286bffdb..c6ef8bae09a3 100755
--- a/tuna-cmd.py
+++ b/tuna-cmd.py
@@ -21,7 +21,7 @@  from functools import reduce
 import tuna.new_eth as ethtool
 import tuna.tuna_sched as tuna_sched
 import procfs
-from tuna import tuna, sysfs
+from tuna import tuna, sysfs, cpupower
 import logging
 import time
 import shutil
@@ -116,7 +116,8 @@  def gen_parser():
             "disable_perf": dict(action='store_true', help="Explicitly disable usage of perf in GUI for process view"),
             "refresh": dict(default=2500, metavar='MSEC', type=int, help="Refresh the GUI every MSEC milliseconds"),
             "priority": dict(default=(None, None), metavar="POLICY:RTPRIO", type=tuna.get_policy_and_rtprio, help="Set thread scheduler tunables: POLICY and RTPRIO"),
-            "background": dict(action='store_true', help="Run command as background task")
+            "background": dict(action='store_true', help="Run command as background task"),
+            "cstate": dict(dest='cstate', metavar='CSTATE', help='Set cpus in IDLE-LIST to a specific cstate'),
          }
 
     parser = HelpMessageParser(description="tuna - Application Tuning Program")
@@ -147,6 +148,7 @@  def gen_parser():
     show_threads = subparser.add_parser('show_threads', description='Show thread list', help='Show thread list')
     show_irqs = subparser.add_parser('show_irqs', description='Show IRQ list', help='Show IRQ list')
     show_configs = subparser.add_parser('show_configs', description='List preloaded profiles', help='List preloaded profiles')
+    cstate = subparser.add_parser('cstate', description='Set a cstate on a given CPU list.', help='Set a cstate on a given CPU list.')
 
     what_is = subparser.add_parser('what_is', description='Provides help about selected entities', help='Provides help about selected entities')
     gui = subparser.add_parser('gui', description="Start the GUI", help="Start the GUI")
@@ -219,6 +221,9 @@  def gen_parser():
     show_irqs_group.add_argument('-S', '--sockets', **MODS['sockets'])
     show_irqs.add_argument('-q', '--irqs', **MODS['irqs'])
 
+    cstate.add_argument('-c', '--cpus', **MODS['cpus'])
+    cstate.add_argument('-i', '--cstate', **MODS['cstate'])
+
     what_is.add_argument('thread_list', **POS['thread_list'])
 
     gui.add_argument('-d', '--disable_perf', **MODS['disable_perf'])
@@ -649,7 +654,6 @@  def main():
     parser = gen_parser()
     # Set all necessary defaults for gui subparser if no arguments provided
     args = parser.parse_args() if len(sys.argv) > 1 else parser.parse_args(['gui'])
-
     if args.debug:
         my_logger = setup_logging("my_logger")
         my_logger.addHandler(add_handler("DEBUG", tofile=False))
@@ -667,6 +671,10 @@  def main():
             print("Valid log levels: NOTSET, DEBUG, INFO, WARNING, ERROR")
             print("Log levels may be specified numerically (0-4)\n")
 
+    if args.cstate:
+        cpupower_controller = cpupower.Cpupower(str(args.cpu_list).strip('[]').replace(' ', ''), args.cstate)
+        cpupower_controller.enable_idle_state()
+
     if 'irq_list' in vars(args):
         ps = procfs.pidstats()
         if tuna.has_threaded_irqs(ps):
diff --git a/tuna/cpupower.py b/tuna/cpupower.py
new file mode 100644
index 000000000000..1a7f324c9fb9
--- /dev/null
+++ b/tuna/cpupower.py
@@ -0,0 +1,80 @@ 
+#! /user/bin/python3
+# SPDX-License-Identifier: GPL-2.0-only
+
+import subprocess
+import argparse
+import os
+import multiprocessing
+import time
+
+
+class Cpupower:
+    def __init__(self, cpulist, cstate):
+        self.cpulist = cpulist
+        self.cstate = cstate
+        self.nstates = len(os.listdir('/sys/devices/system/cpu/cpu0/cpuidle/'))    # number of cstates
+        self.cpu_count = multiprocessing.cpu_count()
+        self.cstate_cfg = []
+
+
+    def enable_idle_state(self):
+        ''' Enable a specific cstate, while disabling all other cstates, and save the current cstate configuration '''
+        self.cstate_cfg = self.get_cstate_cfg()
+
+        # enable cstate and disable the rest
+        if (self.cpulist):
+            subprocess.run(['sudo', 'cpupower', '-c', self.cpulist,'idle-set', '-e', str(self.cstate)], stdout=open(os.devnull, 'wb'))
+            for cs in range(self.nstates):
+                if str(cs) != self.cstate:
+                    subprocess.run(['sudo', 'cpupower', '-c', self.cpulist,'idle-set', '-d', str(cs)], stdout=open(os.devnull, 'wb'))
+        else:
+            subprocess.run(['sudo', 'cpupower', 'idle-set', '-e', str(self.cstate)], stdout=open(os.devnull, 'wb'))
+            for cs in range(self.nstates):
+                if str(cs) != self.cstate:
+                    subprocess.run(['sudo', 'cpupower', 'idle-set', '-d', str(cs)], stdout=open(os.devnull, 'wb'))
+
+        if self.cpulist: print(f'Idlestate {self.cstate} enabled on CPUs {self.cpulist}')
+        else: print(f'Idlestate {self.cstate} enabled on all CPUs')
+
+
+    def get_cstate_cfg(self):
+        ''' Store the current cstate config '''
+        # cstate [m] configuration on cpu [n] can be found in '/sys/devices/system/cpu/cpu*/cpuidle/state*/disable'
+        cfg = []
+        for cpu in range(self.cpu_count):
+            cfg.append([])
+            for cs in range(self.nstates):
+                f = open('/sys/devices/system/cpu/cpu'+str(cpu)+'/cpuidle/state'+str(cs)+'/disable', 'r')
+                d = f.read(1)
+                cfg[cpu].append(d)   # cstate_cfg[n][m] stores the m-th idle state on the n-th cpu
+
+        return cfg
+
+
+    def restore_cstate(self):
+        for cpu in range(self.cpu_count):
+            for cs in range(self.nstates):
+                f = open('/sys/devices/system/cpu/cpu'+str(cpu)+'/cpuidle/state'+str(cs)+'/disable', 'w')
+                f.write(self.cstate_cfg[cpu][cs])
+                f.close()
+        print('Idle state configuration restored')
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-c', '--cpu-list', required=False, default=None,
+                        help='List of cpus to perform cpupower-idle-set operation on.')
+    parser.add_argument('-s', '--cstate', default='',
+                        help='Specify cstate to enable/disable')
+
+    args = parser.parse_args()
+    print(args)
+    cpulist = args.cpu_list
+    cstate = args.cstate
+    cpupower = Cpupower(cpulist, cstate)
+
+    cpupower.enable_idle_state()
+    time.sleep(10)
+    cpupower.restore_cstate()
+
+