[2/3] trace-cruncher: Add example for the high-level histogram APIs

Commit Message

Yordan Karadzhov Jan. 6, 2022, 1:21 p.m. UTC

This is a very basic example, demonstrating the usage of the new
high-level (OOP) APIs for kernel histograms.

Signed-off-by: Yordan Karadzhov (VMware) <[e-mail]>
---
 examples/hist_oop.py | 81 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 examples/hist_oop.py

Patch

diff --git a/examples/hist_oop.py b/examples/hist_oop.py
new file mode 100644
index 0000000..1a3aab6
--- /dev/null
+++ b/examples/hist_oop.py
@@ -0,0 +1,81 @@ 
+#!/usr/bin/env python3
+
+"""
+SPDX-License-Identifier: CC-BY-4.0
+
+Copyright 2021 VMware Inc, Yordan Karadzhov (VMware) <[e-mail]>
+"""
+
+import sys
+import time
+
+import tracecruncher.ft_utils as tc
+
+name = 'khist_example_oop'
+
+cmds = ['start', 'stop', 'show', 'continue', 'clear', 'close']
+
+evt = tc.event('kmem', 'kmalloc')
+
+axes={'call_site': 'sym',
+      'bytes_req': 'n'}
+
+weights=['bytes_alloc']
+
+sort_keys=['bytes_req', 'bytes_alloc']
+
+sort_dir={'bytes_req': 'desc'}
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        sys.exit(1)
+
+    if not sys.argv[1].isdigit() and not sys.argv[1] in cmds:
+        sys.exit(1)
+
+    arg1 = sys.argv[1]
+    if arg1.isdigit() or arg1 == 'start':
+        # Create the kernel tracing histogram.
+        hist = tc.create_khist(name=name, event=evt, axes=axes, weights=weights,
+                               sort_keys=sort_keys, sort_dir=sort_dir)
+        # Start taking data.
+        hist.start()
+
+        if arg1.isdigit():
+            # Take data for a while, then stop, print the result and exit. The
+            # trace-cruncher module will take care for clearing and destroying
+            # the histogram in the kernel.
+            time.sleep(int(arg1))
+            hist.stop()
+            print(hist.data())
+
+        else:
+            # Detach the 'hist' object from the trace-cruncher module. This will
+            # prevent the kernel histogram from being destroyed when the module
+            # is closed (at exit).
+            hist.detach()
+
+    else:
+        # Try to find an existing histogram with the same definition.
+        # The returned histogram is detached from the trace-cruncher module.
+        hist = tc.find_khist(name=name, event=evt, axes=axes, weights=weights,
+                             sort_keys=sort_keys, sort_dir=sort_dir)
+
+        if arg1 == 'stop':
+            # Stop taking data.
+            hist.stop()
+        elif arg1 == 'show':
+            # Print the collected data.
+            print(hist.data())
+        elif arg1 == 'continue':
+            # Continue taking data.
+            hist.resume()
+        elif arg1 == 'clear':
+            # Reset the histogram.
+            hist.clear()
+
+        if arg1 == 'close':
+            # Attach the 'hist' object to the trace-cruncher module. This will
+            # ensure that the kernel histogram will be destroyed when the
+            # module is closed (at exit).
+            hist.attach()