From 736ec1677f1ae7e64f2f3436ca3775c48f79678c Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi <stefanha@redhat.com> Date: Wed, 15 Jan 2014 11:10:30 +0800 Subject: 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> --- scripts/tracetool/backend/simple.py | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) 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, ) -- cgit v1.2.3