From b7d66a761f44a725352e19b64c587924647e6f83 Mon Sep 17 00:00:00 2001
From: Lluís Vilanova <vilanova@ac.upc.edu>
Date: Tue, 6 Dec 2011 17:38:15 +0100
Subject: trace: Provide a per-event status define for conditional compilation
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Adds a 'TRACE_${NAME}_ENABLED' preprocessor define for each tracing event in
"trace.h".

This lets the user conditionally compile code with a relatively high execution
cost that is only necessary when producing the tracing information for an event
that is enabled.

Note that events using this define will probably have the "disable" property by
default, in order to avoid such costs on regular builds.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 scripts/tracetool | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'scripts')

diff --git a/scripts/tracetool b/scripts/tracetool
index 4c9951d0aa..701b517ec1 100755
--- a/scripts/tracetool
+++ b/scripts/tracetool
@@ -519,7 +519,7 @@ linetostap_end_dtrace()
 # Process stdin by calling begin, line, and end functions for the backend
 convert()
 {
-    local begin process_line end str disable
+    local begin process_line end str name NAME enabled
     begin="lineto$1_begin_$backend"
     process_line="lineto$1_$backend"
     end="lineto$1_end_$backend"
@@ -534,8 +534,15 @@ convert()
         # Process the line.  The nop backend handles disabled lines.
         if has_property "$str" "disable"; then
             "lineto$1_nop" "$str"
+            enabled=0
         else
             "$process_line" "$str"
+            enabled=1
+        fi
+        if [ "$1" = "h" ]; then
+            name=$(get_name "$str")
+            NAME=$(echo $name | tr '[:lower:]' '[:upper:]')
+            echo "#define TRACE_${NAME}_ENABLED ${enabled}"
         fi
     done
 
-- 
cgit 1.4.1


From bcec43324d02d586a8bc0c9093623636e870ad19 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Date: Tue, 27 Sep 2011 09:00:22 +0100
Subject: tracetool: Omit useless QEMU_*_ENABLED() check

SystemTap provides a "semaphore" that can optionally be tested before
executing a trace event.  The purpose of this mechanism is to skip
expensive tracing code when the trace event is disabled.

For example, some applications may have trace events that format or
convert strings for trace events.  This expensive processing should only
be done in the case where the trace event is enabled.

Since QEMU's generated trace events never have such special-purpose
code, there is no reason to add the semaphore check.

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 scripts/tracetool | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

(limited to 'scripts')

diff --git a/scripts/tracetool b/scripts/tracetool
index 701b517ec1..65bd0a1b4c 100755
--- a/scripts/tracetool
+++ b/scripts/tracetool
@@ -415,9 +415,7 @@ linetoh_dtrace()
     # Define an empty function for the trace event
     cat <<EOF
 static inline void trace_$name($args) {
-    if (QEMU_${nameupper}_ENABLED()) {
-        QEMU_${nameupper}($argnames);
-    }
+    QEMU_${nameupper}($argnames);
 }
 EOF
 }
-- 
cgit 1.4.1