From 94a420b170b3e997a185a4148accc87bdcd18156 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Sat, 22 May 2010 17:52:39 +0100 Subject: trace: Add trace-events file for declaring trace events This patch introduces the trace-events file where trace events can be declared like so: qemu_malloc(size_t size) "size %zu" qemu_free(void *ptr) "ptr %p" These trace event declarations are processed by a new tool called tracetool to generate code for the trace events. Trace event declarations are independent of the backend tracing system (LTTng User Space Tracing, ftrace markers, DTrace). The default "nop" backend generates empty trace event functions. Therefore trace events are disabled by default. The trace-events file serves two purposes: 1. Adding trace events is easy. It is not necessary to understand the details of a backend tracing system. The trace-events file is a single location where trace events can be declared without code duplication. 2. QEMU is not tightly coupled to one particular backend tracing system. In order to support tracing across QEMU host platforms and to anticipate new backend tracing systems that are currently maturing, it is important to be flexible and not tied to one system. This commit includes fixes from Prerna Saxena and Blue Swirl . Signed-off-by: Stefan Hajnoczi --- trace-events | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 trace-events (limited to 'trace-events') diff --git a/trace-events b/trace-events new file mode 100644 index 0000000..a37d3cc --- /dev/null +++ b/trace-events @@ -0,0 +1,24 @@ +# Trace events for debugging and performance instrumentation +# +# This file is processed by the tracetool script during the build. +# +# To add a new trace event: +# +# 1. Choose a name for the trace event. Declare its arguments and format +# string. +# +# 2. Call the trace event from code using trace_##name, e.g. multiwrite_cb() -> +# trace_multiwrite_cb(). The source file must #include "trace.h". +# +# Format of a trace event: +# +# ( [, ] ...) "" +# +# Example: qemu_malloc(size_t size) "size %zu" +# +# The must be a valid as a C function name. +# +# Types should be standard C types. Use void * for pointers because the trace +# system may not have the necessary headers included. +# +# The should be a sprintf()-compatible format string. -- cgit v1.1