trace: Conditionally trace events based on their per-vCPU state

Events with the 'vcpu' property are conditionally emitted according to
their per-vCPU state. Other events are emitted normally based on their
global tracing state.

Note that the per-vCPU condition check applies to all tracing backends.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 16 insertions, 10 deletions

diff --git a/scripts/tracetool/backend/log.py b/scripts/tracetool/backend/log.py
index e409b7326e..b3ff064011 100644
--- a/scripts/tracetool/backend/log.py
+++ b/scripts/tracetool/backend/log.py
@@ -6,7 +6,7 @@ Stderr built-in backend.
 """
 
 __author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
-__copyright__  = "Copyright 2012-2014, Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012-2016, Lluís Vilanova <vilanova@ac.upc.edu>"
 __license__    = "GPL version 2 or (at your option) any later version"
 
 __maintainer__ = "Stefan Hajnoczi"
@@ -30,15 +30,21 @@ def generate_h(event):
     if len(event.args) > 0:
         argnames = ", " + argnames
 
-    out('    if (trace_event_get_state(%(event_id)s)) {',
-        '        struct timeval _now;',
-        '        gettimeofday(&_now, NULL);',
-        '        qemu_log_mask(LOG_TRACE, "%%d@%%zd.%%06zd:%(name)s " %(fmt)s "\\n",',
-        '                      getpid(),',
-        '                      (size_t)_now.tv_sec, (size_t)_now.tv_usec',
-        '                      %(argnames)s);',
-        '    }',
-        event_id="TRACE_" + event.name.upper(),
+    if "vcpu" in event.properties:
+        # already checked on the generic format code
+        cond = "true"
+    else:
+        cond = "trace_event_get_state(%s)" % ("TRACE_" + event.name.upper())
+
+    out('        if (%(cond)s) {',
+        '            struct timeval _now;',
+        '            gettimeofday(&_now, NULL);',
+        '            qemu_log_mask(LOG_TRACE, "%%d@%%zd.%%06zd:%(name)s " %(fmt)s "\\n",',
+        '                          getpid(),',
+        '                          (size_t)_now.tv_sec, (size_t)_now.tv_usec',
+        '                          %(argnames)s);',
+        '        }',
+        cond=cond,
         name=event.name,
         fmt=event.fmt.rstrip("\n"),
         argnames=argnames)