Re: [patch for 2.6.26 1/7] Markers - define non optimized marker (updated)

Mathieu Desnoyers
2008-03-28T01:04:56Z

Markers - define non optimized marker

To support the forthcoming "immediate values" marker optimization, we must have
a way to declare markers in few code paths that does not use instruction
modification based enable. This will be the case of printk(), some traps and
eventually lockdep instrumentation.

Changelog :
- Fix reversed boolean logic of "generic".

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---
include/linux/marker.h | 29 ++++++++++++++++++++++++-----
1 file changed, 24 insertions(+), 5 deletions(-)

Index: linux-2.6-lttng/include/linux/marker.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/marker.h 2008-03-27 20:47:44.000000000 -0400
+++ linux-2.6-lttng/include/linux/marker.h 2008-03-27 20:49:04.000000000 -0400
@@ -58,8 +58,12 @@ struct marker {
* Make sure the alignment of the structure in the __markers section will
* not add unwanted padding between the beginning of the section and the
* structure. Force alignment to the same alignment as the section start.
+ *
+ * The "generic" argument controls which marker enabling mechanism must be used.
+ * If generic is true, a variable read is used.
+ * If generic is false, immediate values are used.
*/
-#define __trace_mark(name, call_private, format, args...) \
+#define __trace_mark(generic, name, call_private, format, args...) \
do { \
static const char __mstrtab_##name[] \
__attribute__((section("__markers_strings"))) \
@@ -79,7 +83,7 @@ struct marker {
extern void marker_update_probe_range(struct marker *begin,
struct marker *end);
#else /* !CONFIG_MARKERS */
-#define __trace_mark(name, call_private, format, args...) \
+#define __trace_mark(generic, name, call_private, format, args...) \
__mark_check_format(format, ## args)
static inline void marker_update_probe_range(struct marker *begin,
struct marker *end)
@@ -87,15 +91,30 @@ static inline void marker_update_probe_r
#endif /* CONFIG_MARKERS */

/**
- * trace_mark - Marker
+ * trace_mark - Marker using code patching
* @name: marker name, not quoted.
* @format: format string
* @args...: variable argument list
*
- * Places a marker.
+ * Places a marker using optimized code patching technique (imv_read())
+ * to be enabled when immediate values are present.
*/
#define trace_mark(name, format, args...) \
- __trace_mark(name, NULL, format, ## args)
+ __trace_mark(0, name, NULL, format, ## args)
+
+/**
+ * _trace_mark - Marker using variable read
+ * @name: marker name, not quoted.
+ * @format: format string
+ * @args...: variable argument list
+ *
+ * Places a marker using a standard memory read (_imv_read()) to be
+ * enabled. Should be used for markers in code paths where instruction
+ * modification based enabling is not welcome. (__init and __exit functions,
+ * lockdep, some traps, printk).
+ */
+#define _trace_mark(name, format, args...) \
+ __trace_mark(1, name, NULL, format, ## args)

/**
* MARK_NOARGS - Format string for a marker with no argument.
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68