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Commit 97ea1a7f authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
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perf tools: Fix thread comm resolution in perf sched 



This reverts commit 9a92b479 ("perf
tools: Improve thread comm resolution in perf sched") and fixes the
real bug.

The bug was elsewhere:

We are failing to resolve thread names in perf sched because the
table of threads we are building, on top of comm events, has a per
process granularity. But perf sched, unlike the other perf tools,
needs a per thread granularity as we are profiling every tasks
individually.

So fix it by building our threads table using the tid instead of
the pid as the thread identifier.

v2: Revert the previous fix - it is not really needed

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1255028657-11158-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 2e538c4a

tools/perf/builtin-sched.c

+6 −40
Original line number Diff line number Diff line
@@ -638,7 +638,7 @@ process_comm_event(event_t *event, unsigned long offset, unsigned long head) 
{

	struct thread *thread;



	thread = threads__findnew(event->comm.pid, &threads, &last_match);

	thread = threads__findnew(event->comm.tid, &threads, &last_match);



	dump_printf("%p [%p]: perf_event_comm: %s:%d\n",

		(void *)(offset + head),
@@ -1034,36 +1034,6 @@ add_sched_in_event(struct work_atoms *atoms, u64 timestamp) 
	atoms->nb_atoms++;

}



static struct thread *

threads__findnew_from_ctx(u32 pid, struct trace_switch_event *switch_event)

{

	struct thread *th;



	th = threads__findnew_nocomm(pid, &threads, &last_match);

	if (th->comm)

		return th;



	if (pid == switch_event->prev_pid)

		thread__set_comm(th, switch_event->prev_comm);

	else

		thread__set_comm(th, switch_event->next_comm);

	return th;

}



static struct thread *

threads__findnew_from_wakeup(struct trace_wakeup_event *wakeup_event)

{

	struct thread *th;



	th =  threads__findnew_nocomm(wakeup_event->pid, &threads, &last_match);

	if (th->comm)

		return th;



	thread__set_comm(th, wakeup_event->comm);



	return th;

}



static void

latency_switch_event(struct trace_switch_event *switch_event,

		     struct event *event __used,
@@ -1089,10 +1059,8 @@ latency_switch_event(struct trace_switch_event *switch_event, 
		die("hm, delta: %Ld < 0 ?\n", delta);





	sched_out = threads__findnew_from_ctx(switch_event->prev_pid,

					      switch_event);

	sched_in = threads__findnew_from_ctx(switch_event->next_pid,

					     switch_event);

	sched_out = threads__findnew(switch_event->prev_pid, &threads, &last_match);

	sched_in = threads__findnew(switch_event->next_pid, &threads, &last_match);



	out_events = thread_atoms_search(&atom_root, sched_out, &cmp_pid);

	if (!out_events) {
@@ -1158,7 +1126,7 @@ latency_wakeup_event(struct trace_wakeup_event *wakeup_event, 
	if (!wakeup_event->success)

		return;



	wakee = threads__findnew_from_wakeup(wakeup_event);

	wakee = threads__findnew(wakeup_event->pid, &threads, &last_match);

	atoms = thread_atoms_search(&atom_root, wakee, &cmp_pid);

	if (!atoms) {

		thread_atoms_insert(wakee);
@@ -1418,10 +1386,8 @@ map_switch_event(struct trace_switch_event *switch_event, 
		die("hm, delta: %Ld < 0 ?\n", delta);





	sched_out = threads__findnew_from_ctx(switch_event->prev_pid,

					      switch_event);

	sched_in = threads__findnew_from_ctx(switch_event->next_pid,

					     switch_event);

	sched_out = threads__findnew(switch_event->prev_pid, &threads, &last_match);

	sched_in = threads__findnew(switch_event->next_pid, &threads, &last_match);



	curr_thread[this_cpu] = sched_in;

tools/perf/util/thread.c

+7 −25
Original line number Diff line number Diff line
@@ -6,17 +6,15 @@ 
#include "util.h"

#include "debug.h"



static struct thread *thread__new(pid_t pid, int set_comm)

static struct thread *thread__new(pid_t pid)

{

	struct thread *self = calloc(1, sizeof(*self));



	if (self != NULL) {

		self->pid = pid;

		if (set_comm) {

		self->comm = malloc(32);

		if (self->comm)

			snprintf(self->comm, 32, ":%d", self->pid);

		}

		self->maps = RB_ROOT;

		INIT_LIST_HEAD(&self->removed_maps);

	}
@@ -52,10 +50,8 @@ static size_t thread__fprintf(struct thread *self, FILE *fp) 
	return ret;

}



static struct thread *

__threads__findnew(pid_t pid, struct rb_root *threads,

		   struct thread **last_match,

		   int set_comm)

struct thread *

threads__findnew(pid_t pid, struct rb_root *threads, struct thread **last_match)

{

	struct rb_node **p = &threads->rb_node;

	struct rb_node *parent = NULL;
@@ -84,8 +80,7 @@ __threads__findnew(pid_t pid, struct rb_root *threads, 
			p = &(*p)->rb_right;

	}



	th = thread__new(pid, set_comm);



	th = thread__new(pid);

	if (th != NULL) {

		rb_link_node(&th->rb_node, parent, p);

		rb_insert_color(&th->rb_node, threads);
@@ -95,19 +90,6 @@ __threads__findnew(pid_t pid, struct rb_root *threads, 
	return th;

}



struct thread *

threads__findnew(pid_t pid, struct rb_root *threads, struct thread **last_match)

{

	return __threads__findnew(pid, threads, last_match, 1);

}



struct thread *

threads__findnew_nocomm(pid_t pid, struct rb_root *threads,

			struct thread **last_match)

{

	return __threads__findnew(pid, threads, last_match, 0);

}



struct thread *

register_idle_thread(struct rb_root *threads, struct thread **last_match)

{

tools/perf/util/thread.h

+0 −3
Original line number Diff line number Diff line
@@ -18,9 +18,6 @@ int thread__set_comm(struct thread *self, const char *comm); 
struct thread *

threads__findnew(pid_t pid, struct rb_root *threads, struct thread **last_match);

struct thread *

threads__findnew_nocomm(pid_t pid, struct rb_root *threads,

			struct thread **last_match);

struct thread *

register_idle_thread(struct rb_root *threads, struct thread **last_match);

void thread__insert_map(struct thread *self, struct map *map);

int thread__fork(struct thread *self, struct thread *parent);