python: tools: Add tool for displaying a tree of PSI data

Add a tool for displaying the PSI data for a cgroup hierarchy.

$ ./src/tools/cgpsitree.py -c cpu -f some-total -d 1
cpu some-total PSI data
/: 516797584
├── dev-hugepages.mount: 7
├── dev-mqueue.mount: 0
├── init.scope: 117064
├── machine.slice: 0
├── proc-sys-fs-binfmt_misc.mount: 3
├── sys-fs-fuse-connections.mount: 3
├── sys-kernel-config.mount: 0
├── sys-kernel-debug.mount: 109
├── sys-kernel-tracing.mount: 3
├── system.slice: 58977534
└── user.slice: 425882912

$ ./src/tools/cgpsitree.py -c memory -f full-avg60 -d 1
memory full-avg60 PSI data
/: 0.0
├── dev-hugepages.mount: 0.0
├── dev-mqueue.mount: 0.0
├── init.scope: 0.0
├── machine.slice: 0.0
├── proc-sys-fs-binfmt_misc.mount: 0.0
├── sys-fs-fuse-connections.mount: 0.0
├── sys-kernel-config.mount: 0.0
├── sys-kernel-debug.mount: 0.0
├── sys-kernel-tracing.mount: 0.0
├── system.slice: 0.0
└── user.slice: 0.0

Signed-off-by: Tom Hromatka <[email protected]>

src/python/libcgroup.pyx.m4

@@ -93,7 +93,7 @@ cdef class Cgroup:
     """ Python object representing a libcgroup cgroup """
     cdef cgroup.cgroup * _cgp
     cdef public:
-        object name, controllers, version, path, children, settings, pids
+        object name, controllers, version, path, children, settings, pids, psi
 
     @staticmethod
     def cgroup_init():
@@ -127,6 +127,7 @@ cdef class Cgroup:
         self.children = list()
         self.settings = dict()
         self.pids = list()
+        self.psi = dict()
 
     def __str__(self):
         out_str = "Cgroup {}\n".`format'(self.name)
@@ -138,6 +139,8 @@ cdef class Cgroup:
         out_str += indent("pids = {}\n".`format'(`len'(self.pids)), 4)
         for key, value in self.settings.items():
             out_str += indent("settings[{}] = {}\n".`format'(key, value), 4)
+        for key, value in self.psi.items():
+            out_str += indent("psi[{}] = {}\n".`format'(key, value), 4)
 
         return out_str
 
@@ -870,6 +873,35 @@ cdef class Cgroup:
 
             self.settings[setting] = value
 
+    def _parse_psi_line(self, line):
+        entries = line.split()
+        for i, entry in enumerate(entries):
+            if i == 0:
+                continue
+            key = '{}-{}'.`format'(entries[0], entry.split('=')[0])
+
+            if 'total' in key:
+                self.psi[key] = int(entry.split('=')[1])
+            else:
+                self.psi[key] = float(entry.split('=')[1])
+
+    def get_psi(self, controller):
+        """Get the PSI data for this cgroup and controller
+
+        Arguments:
+        controller - PSI data to obtain - cpu, memory, or io
+        """
+        if not type(CgroupFile):
+            raise CgroupError('PSI data can only be gathered on cgroup directories: {}'.`format'(self.path))
+
+        setting = '{}.pressure'.`format'(controller)
+
+        self.add_setting(setting)
+        self.cgxget()
+
+        for line in self.controllers[controller].settings[setting].splitlines():
+            self._parse_psi_line(line)
+
     def __dealloc__(self):
         cgroup.cgroup_free(&self._cgp)
 
@@ -1036,6 +1068,24 @@ class LibcgroupTree(object):
         else:
             self.tree.show()
 
+class LibcgroupPsiTree(LibcgroupTree):
+    def __init__(self, name, controller='cpu', depth=None, psi_field='some-avg10'):
+        super().__init__(name, version=Version.CGROUP_V2, files=False, depth=depth)
+
+        self.rootcg.get_psi(controller)
+        self.psi_field = psi_field
+
+    def walk_action(self, cg):
+        cg.get_psi(self.controller)
+        super().walk_action(cg)
+
+    def node_label(self, cg):
+        name = os.path.basename(cg.name)
+        if not `len'(name):
+            name = '/'
+
+        return '{}: {}'.`format'(name, cg.psi[self.psi_field])
+
 float_metrics = ['%usr', '%system', '%guest', '%wait', '%CPU', '%MEM', 'minflt/s', 'majflt/s']
 int_metrics = ['Time', 'UID', 'PID', 'CPU', 'RSS', 'threads', 'fd-nr']
 str_metrics = ['Command']

src/tools/cgpsitree.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: LGPL-2.1-only
+#
+# Display the PSI usage in a cgroup hierarchy
+#
+# Copyright (c) 2021-2024 Oracle and/or its affiliates.
+# Author: Tom Hromatka <[email protected]>
+#
+
+from libcgroup import LibcgroupPsiTree
+import argparse
+import os
+
+def parse_args():
+    parser = argparse.ArgumentParser("Libcgroup PSI Tree")
+    parser.add_argument('-C', '--cgroup', type=str, required=False, default=None,
+                        help='Relative path to the cgroup of interest, e.g. machine.slice/foo.scope')
+    parser.add_argument('-c', '--controller', required=True,
+                        help='PSI controller data to display.  cpu, io, or memory')
+    parser.add_argument('-f', '--field', required=False, default='some-avg10',
+                        help='Which PSI field to display, e.g. some-avg10, full-avg60, ...')
+    parser.add_argument('-d', '--depth', type=int, required=False, default=None,
+                        help='Depth to recurse into the cgroup path.  0 == only this cgroup, 1 == this cgroup and its children, ...')
+
+    args = parser.parse_args()
+
+    return args
+
+def main(args):
+    cgtree = LibcgroupPsiTree(args.cgroup, controller=args.controller, depth=args.depth,
+                              psi_field=args.field)
+
+    cgtree.walk()
+    cgtree.build()
+
+    print('{} {} PSI data'.format(args.controller, args.field))
+    cgtree.show()
+
+if __name__ == '__main__':
+    args = parse_args()
+    main(args)