Commit e6dab5ff authored by Andrew Vagin's avatar Andrew Vagin Committed by Ingo Molnar
Browse files

perf/trace: Add ability to set a target task for events 



A few events are interesting not only for a current task.
For example, sched_stat_* events are interesting for a task
which wakes up. For this reason, it will be good if such
events will be delivered to a target task too.

Now a target task can be set by using __perf_task().

The original idea and a draft patch belongs to Peter Zijlstra.

I need these events for profiling sleep times. sched_switch is used for
getting callchains and sched_stat_* is used for getting time periods.
These events are combined in user space, then it can be analyzed by
perf tools.

Inspired-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arun Sharma <asharma@fb.com>
Signed-off-by: default avatarAndrew Vagin <avagin@openvz.org>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1342016098-213063-1-git-send-email-avagin@openvz.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent d07bdfd3

include/linux/ftrace_event.h

+3 −2
Original line number Diff line number Diff line
@@ -306,9 +306,10 @@ extern void *perf_trace_buf_prepare(int size, unsigned short type, 


static inline void

perf_trace_buf_submit(void *raw_data, int size, int rctx, u64 addr,

		       u64 count, struct pt_regs *regs, void *head)

		       u64 count, struct pt_regs *regs, void *head,

		       struct task_struct *task)

{

	perf_tp_event(addr, count, raw_data, size, regs, head, rctx);

	perf_tp_event(addr, count, raw_data, size, regs, head, rctx, task);

}

#endif

include/linux/perf_event.h

+2 −1
Original line number Diff line number Diff line
@@ -1272,7 +1272,8 @@ static inline bool perf_paranoid_kernel(void) 
extern void perf_event_init(void);

extern void perf_tp_event(u64 addr, u64 count, void *record,

			  int entry_size, struct pt_regs *regs,

			  struct hlist_head *head, int rctx);

			  struct hlist_head *head, int rctx,

			  struct task_struct *task);

extern void perf_bp_event(struct perf_event *event, void *data);



#ifndef perf_misc_flags

include/trace/events/sched.h

+4 −0
Original line number Diff line number Diff line
@@ -73,6 +73,9 @@ DECLARE_EVENT_CLASS(sched_wakeup_template, 
		__entry->prio		= p->prio;

		__entry->success	= success;

		__entry->target_cpu	= task_cpu(p);

	)

	TP_perf_assign(

		__perf_task(p);

	),



	TP_printk("comm=%s pid=%d prio=%d success=%d target_cpu=%03d",
@@ -325,6 +328,7 @@ DECLARE_EVENT_CLASS(sched_stat_template, 
	)

	TP_perf_assign(

		__perf_count(delay);

		__perf_task(tsk);

	),



	TP_printk("comm=%s pid=%d delay=%Lu [ns]",

include/trace/ftrace.h

+5 −1
Original line number Diff line number Diff line
@@ -712,6 +712,9 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call 
#undef __perf_count

#define __perf_count(c) __count = (c)



#undef __perf_task

#define __perf_task(t) __task = (t)



#undef TP_perf_assign

#define TP_perf_assign(args...) args
@@ -725,6 +728,7 @@ perf_trace_##call(void *__data, proto) \ 
	struct ftrace_raw_##call *entry;				\

	struct pt_regs __regs;						\

	u64 __addr = 0, __count = 1;					\

	struct task_struct *__task = NULL;				\

	struct hlist_head *head;					\

	int __entry_size;						\

	int __data_size;						\
@@ -752,7 +756,7 @@ perf_trace_##call(void *__data, proto) \ 
									\

	head = this_cpu_ptr(event_call->perf_events);			\

	perf_trace_buf_submit(entry, __entry_size, rctx, __addr,	\

		__count, &__regs, head);				\

		__count, &__regs, head, __task);			\

}



/*

kernel/events/callchain.c

+8 −1
Original line number Diff line number Diff line
@@ -153,7 +153,8 @@ put_callchain_entry(int rctx) 
	put_recursion_context(__get_cpu_var(callchain_recursion), rctx);

}



struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)

struct perf_callchain_entry *

perf_callchain(struct perf_event *event, struct pt_regs *regs)

{

	int rctx;

	struct perf_callchain_entry *entry;
@@ -178,6 +179,12 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) 
	}



	if (regs) {

		/*

		 * Disallow cross-task user callchains.

		 */

		if (event->ctx->task && event->ctx->task != current)

			goto exit_put;



		perf_callchain_store(entry, PERF_CONTEXT_USER);

		perf_callchain_user(entry, regs);

	}

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