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Commit 8a58a34b authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Steven Rostedt (VMware)
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timers: Make flags output in the timer_start tracepoint useful 

The timer flags in the timer_start trace event contain lots of useful
information, but the meaning is not clear in the trace output. Making tools
rely on the bit positions is bad as they might change over time.

Decode the flags in the print out. Tools can retrieve the bits and their
meaning from the trace format file.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1702101639290.4036@nanos



Requested-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 1f9b3546

include/linux/timer.h

+2 −0
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ struct timer_list { 
#define TIMER_ARRAYSHIFT	22

#define TIMER_ARRAYMASK		0xFFC00000



#define TIMER_TRACE_FLAGMASK	(TIMER_MIGRATING | TIMER_DEFERRABLE | TIMER_PINNED | TIMER_IRQSAFE)



#define __TIMER_INITIALIZER(_function, _expires, _data, _flags) { \

		.entry = { .next = TIMER_ENTRY_STATIC },	\

		.function = (_function),			\

include/trace/events/timer.h

+12 −2
Original line number Diff line number Diff line
@@ -36,6 +36,13 @@ DEFINE_EVENT(timer_class, timer_init, 
	TP_ARGS(timer)

);



#define decode_timer_flags(flags)			\

	__print_flags(flags, "|",			\

		{  TIMER_MIGRATING,	"M" },		\

		{  TIMER_DEFERRABLE,	"D" },		\

		{  TIMER_PINNED,	"P" },		\

		{  TIMER_IRQSAFE,	"I" })



/**

 * timer_start - called when the timer is started

 * @timer:	pointer to struct timer_list
@@ -65,9 +72,12 @@ TRACE_EVENT(timer_start, 
		__entry->flags		= flags;

	),



	TP_printk("timer=%p function=%pf expires=%lu [timeout=%ld] flags=0x%08x",

	TP_printk("timer=%p function=%pf expires=%lu [timeout=%ld] cpu=%u idx=%u flags=%s",

		  __entry->timer, __entry->function, __entry->expires,

		  (long)__entry->expires - __entry->now, __entry->flags)

		  (long)__entry->expires - __entry->now,

		  __entry->flags & TIMER_CPUMASK,

		  __entry->flags >> TIMER_ARRAYSHIFT,

		  decode_timer_flags(__entry->flags & TIMER_TRACE_FLAGMASK))

);



/**