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| author | Stefan Hajnoczi <stefanha@redhat.com> | 2014-01-15 11:10:30 +0800 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-01-27 15:49:39 +0100 |
| commit | 736ec1677f1ae7e64f2f3436ca3775c48f79678c (patch) | |
| tree | 48db2dfcfc0a028a2a427b5b9c537c4a389aa705 /scripts | |
| parent | 05735a2a9cf37f5dc11ece998906431dda707258 (diff) | |
| download | qemu-736ec1677f1ae7e64f2f3436ca3775c48f79678c.tar.gz | |
trace: fix simple trace "disable" keyword
The trace-events "disable" keyword turns an event into a nop at
compile-time. This is important for high-frequency events that can
impact performance.
The "disable" keyword is currently broken in the simple trace backend.
This patch fixes the problem as follows:
Trace events are identified by their TraceEventID number. When events
are disabled there are two options for assigning TraceEventID numbers:
1. Skip disabled events and don't assign them a number.
2. Assign numbers for all events regardless of the disabled keyword.
The simple trace backend and its binary file format uses approach #1.
The tracetool infrastructure has been using approach #2 for a while.
The result is that the numbers used in simple trace files do not
correspond with TraceEventIDs. In trace/simple.c we assumed that they
are identical and therefore emitted bogus numbers.
This patch fixes the bug by using TraceEventID for trace_event_id()
while sticking to approach #1 for simple trace file numbers. This
preserves simple trace file format compatibility.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'scripts')
| -rw-r--r-- | scripts/tracetool/backend/simple.py | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/scripts/tracetool/backend/simple.py b/scripts/tracetool/backend/simple.py index 30faac93c8..3dde372e46 100644 --- a/scripts/tracetool/backend/simple.py +++ b/scripts/tracetool/backend/simple.py @@ -56,7 +56,7 @@ def c(events): out('', - ' TraceEvent *eventp = trace_event_id(%(event_id)s);', + ' TraceEvent *eventp = trace_event_id(%(event_enum)s);', ' bool _state = trace_event_get_state_dynamic(eventp);', ' if (!_state) {', ' return;', @@ -65,6 +65,7 @@ def c(events): ' if (trace_record_start(&rec, %(event_id)s, %(size_str)s)) {', ' return; /* Trace Buffer Full, Event Dropped ! */', ' }', + event_enum = 'TRACE_' + event.name.upper(), event_id = num, size_str = sizestr, ) |