tools/power/x86/intel_pstate_tracer: Free the trace buffer memory

The trace buffer memory should be, mostly, freed after
the buffer has been output.

This patch is required before a future patch that will allow
the user to override the default, and specify the trace buffer
memory allocation as a command line option.

Signed-off-by: Doug Smythies <dsmythies@telus.net>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

tools/power/x86/intel_pstate_tracer/intel_pstate_tracer.py

@@ -411,6 +411,16 @@ def set_trace_buffer_size():
         print('IO error setting trace buffer size ')
         quit()
 
+def free_trace_buffer():
+    """ Free the trace buffer memory """
+
+    try:
+       open('/sys/kernel/debug/tracing/buffer_size_kb'
+                 , 'w').write("1")
+    except:
+        print('IO error setting trace buffer size ')
+        quit()
+
 def read_trace_data(filename):
     """ Read and parse trace data """
 
@@ -583,4 +593,9 @@ def read_trace_data(filename):
     for f in files:
         fix_ownership(f)
 
+clear_trace_file()
+# Free the memory
+if interval:
+    free_trace_buffer()
+
 os.chdir('../../')