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| author | Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> | 2008-11-14 17:47:47 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-11-16 09:01:36 +0100 |
| commit | 7e066fb870fcd1025ec3ba7bbde5d541094f4ce1 (patch) | |
| tree | 52acda06de25c029b9834110d7bf6b4abc50353b /Documentation/tracepoints.txt | |
| parent | 32f85742778dfc2c74975cf0b9f5bdb13470cb32 (diff) | |
| download | lwn-7e066fb870fcd1025ec3ba7bbde5d541094f4ce1.tar.gz lwn-7e066fb870fcd1025ec3ba7bbde5d541094f4ce1.zip | |
tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()
Impact: API *CHANGE*. Must update all tracepoint users.
Add DEFINE_TRACE() to tracepoints to let them declare the tracepoint
structure in a single spot for all the kernel. It helps reducing memory
consumption, especially when declaring a lot of tracepoints, e.g. for
kmalloc tracing.
*API CHANGE WARNING*: now, DECLARE_TRACE() must be used in headers for
tracepoint declarations rather than DEFINE_TRACE(). This is the sane way
to do it. The name previously used was misleading.
Updates scheduler instrumentation to follow this API change.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/tracepoints.txt')
| -rw-r--r-- | Documentation/tracepoints.txt | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/Documentation/tracepoints.txt b/Documentation/tracepoints.txt index 5d354e167494..e8ad47b437f3 100644 --- a/Documentation/tracepoints.txt +++ b/Documentation/tracepoints.txt @@ -42,7 +42,7 @@ In include/trace/subsys.h : #include <linux/tracepoint.h> -DEFINE_TRACE(subsys_eventname, +DECLARE_TRACE(subsys_eventname, TPPTOTO(int firstarg, struct task_struct *p), TPARGS(firstarg, p)); @@ -50,6 +50,8 @@ In subsys/file.c (where the tracing statement must be added) : #include <trace/subsys.h> +DEFINE_TRACE(subsys_eventname); + void somefct(void) { ... @@ -86,6 +88,9 @@ to limit collisions. Tracepoint names are global to the kernel: they are considered as being the same whether they are in the core kernel image or in modules. +If the tracepoint has to be used in kernel modules, an +EXPORT_TRACEPOINT_SYMBOL_GPL() or EXPORT_TRACEPOINT_SYMBOL() can be used to +export the defined tracepoints. * Probe / tracepoint example |