287050d390
There are instances in the kernel that we only want to trace a tracepoint when a certain condition is set. But we do not want to test for that condition in the core kernel. If we test for that condition before calling the tracepoin, then we will be performing that test even when tracing is not enabled. This is 99.99% of the time. We currently can just filter out on that condition, but that happens after we write to the trace buffer. We just wasted time writing to the ring buffer for an event we never cared about. This patch adds: TRACE_EVENT_CONDITION() and DEFINE_EVENT_CONDITION() These have a new TP_CONDITION() argument that comes right after the TP_ARGS(). This condition can use the parameters of TP_ARGS() in the TRACE_EVENT() to determine if the tracepoint should be traced or not. The TP_CONDITION() will be placed in a if (cond) trace; For example, for the tracepoint sched_wakeup, it is useless to trace a wakeup event where the caller never actually wakes anything up (where success == 0). So adding: TP_CONDITION(success), which uses the "success" parameter of the wakeup tracepoint will have it only trace when we have successfully woken up a task. Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
114 lines
3.0 KiB
C
114 lines
3.0 KiB
C
/*
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* Trace files that want to automate creationg of all tracepoints defined
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* in their file should include this file. The following are macros that the
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* trace file may define:
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*
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* TRACE_SYSTEM defines the system the tracepoint is for
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*
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* TRACE_INCLUDE_FILE if the file name is something other than TRACE_SYSTEM.h
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* This macro may be defined to tell define_trace.h what file to include.
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* Note, leave off the ".h".
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*
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* TRACE_INCLUDE_PATH if the path is something other than core kernel include/trace
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* then this macro can define the path to use. Note, the path is relative to
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* define_trace.h, not the file including it. Full path names for out of tree
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* modules must be used.
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*/
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#ifdef CREATE_TRACE_POINTS
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/* Prevent recursion */
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#undef CREATE_TRACE_POINTS
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#include <linux/stringify.h>
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#undef TRACE_EVENT
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#define TRACE_EVENT(name, proto, args, tstruct, assign, print) \
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DEFINE_TRACE(name)
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#undef TRACE_EVENT_CONDITION
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#define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \
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TRACE_EVENT(name, \
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PARAMS(proto), \
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PARAMS(args), \
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PARAMS(tstruct), \
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PARAMS(assign), \
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PARAMS(print))
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#undef TRACE_EVENT_FN
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#define TRACE_EVENT_FN(name, proto, args, tstruct, \
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assign, print, reg, unreg) \
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DEFINE_TRACE_FN(name, reg, unreg)
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#undef DEFINE_EVENT
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#define DEFINE_EVENT(template, name, proto, args) \
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DEFINE_TRACE(name)
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#undef DEFINE_EVENT_PRINT
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#define DEFINE_EVENT_PRINT(template, name, proto, args, print) \
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DEFINE_TRACE(name)
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#undef DEFINE_EVENT_CONDITION
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#define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \
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DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))
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#undef DECLARE_TRACE
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#define DECLARE_TRACE(name, proto, args) \
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DEFINE_TRACE(name)
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#undef TRACE_INCLUDE
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#undef __TRACE_INCLUDE
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#ifndef TRACE_INCLUDE_FILE
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# define TRACE_INCLUDE_FILE TRACE_SYSTEM
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# define UNDEF_TRACE_INCLUDE_FILE
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#endif
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#ifndef TRACE_INCLUDE_PATH
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# define __TRACE_INCLUDE(system) <trace/events/system.h>
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# define UNDEF_TRACE_INCLUDE_PATH
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#else
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# define __TRACE_INCLUDE(system) __stringify(TRACE_INCLUDE_PATH/system.h)
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#endif
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# define TRACE_INCLUDE(system) __TRACE_INCLUDE(system)
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/* Let the trace headers be reread */
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#define TRACE_HEADER_MULTI_READ
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#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
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/* Make all open coded DECLARE_TRACE nops */
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#undef DECLARE_TRACE
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#define DECLARE_TRACE(name, proto, args)
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#ifdef CONFIG_EVENT_TRACING
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#include <trace/ftrace.h>
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#endif
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#undef TRACE_EVENT
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#undef TRACE_EVENT_FN
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#undef TRACE_EVENT_CONDITION
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#undef DECLARE_EVENT_CLASS
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#undef DEFINE_EVENT
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#undef DEFINE_EVENT_PRINT
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#undef DEFINE_EVENT_CONDITION
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#undef TRACE_HEADER_MULTI_READ
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#undef DECLARE_TRACE
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/* Only undef what we defined in this file */
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#ifdef UNDEF_TRACE_INCLUDE_FILE
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# undef TRACE_INCLUDE_FILE
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# undef UNDEF_TRACE_INCLUDE_FILE
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#endif
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#ifdef UNDEF_TRACE_INCLUDE_PATH
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# undef TRACE_INCLUDE_PATH
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# undef UNDEF_TRACE_INCLUDE_PATH
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#endif
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/* We may be processing more files */
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#define CREATE_TRACE_POINTS
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#endif /* CREATE_TRACE_POINTS */
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