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Date: Mon, 14 Jul 2014 17:18:29 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...il.com>,
Paul Mackerras <paulus@...ba.org>,
Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 02/41] perf tools: Fix map groups of threads with unknown
pids
Em Mon, Jul 14, 2014 at 01:02:26PM +0300, Adrian Hunter escreveu:
> Events like sched_switch do not provide a pid (tgid)
> which can result in threads with an unknown pid. If
> the pid is later discovered, join the map groups.
> Note the thread's map groups should be empty because
> they are populated by MMAP events which do provide the
> pid and tid.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
> tools/perf/util/machine.c | 22 ++++++++++++++++------
> tools/perf/util/map.c | 14 ++++++++++++++
> tools/perf/util/map.h | 1 +
> tools/perf/util/thread.c | 35 +++++++++++++++++++++++++++++++++++
> tools/perf/util/thread.h | 1 +
> 5 files changed, 67 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 5b80877..0fa93c1 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -272,6 +272,17 @@ void machines__set_id_hdr_size(struct machines *machines, u16 id_hdr_size)
> return;
> }
>
> +static void machine__update_thread_pid(struct machine *machine,
> + struct thread *th, pid_t pid)
> +{
> + if (pid != th->pid_ && pid != -1 && th->pid_ == -1) {
> + th->pid_ = pid;
> + if (thread__join_map_groups(th, machine))
> + pr_err("Failed to join map groups for %d:%d\n",
> + th->pid_, th->tid);
> + }
> +}
> +
I think you should combine the above function with
thread__join_map_groups, and I think that the method belongs to the
'machine' class, see below for further comments on this...
> static struct thread *__machine__findnew_thread(struct machine *machine,
> pid_t pid, pid_t tid,
> bool create)
> @@ -285,10 +296,10 @@ static struct thread *__machine__findnew_thread(struct machine *machine,
> * so most of the time we dont have to look up
> * the full rbtree:
> */
> - if (machine->last_match && machine->last_match->tid == tid) {
> - if (pid != -1 && pid != machine->last_match->pid_)
> - machine->last_match->pid_ = pid;
> - return machine->last_match;
> + th = machine->last_match;
> + if (th && th->tid == tid) {
> + machine__update_thread_pid(machine, th, pid);
> + return th;
> }
>
> while (*p != NULL) {
> @@ -297,8 +308,7 @@ static struct thread *__machine__findnew_thread(struct machine *machine,
>
> if (th->tid == tid) {
> machine->last_match = th;
> - if (pid != -1 && pid != th->pid_)
> - th->pid_ = pid;
> + machine__update_thread_pid(machine, th, pid);
> return th;
> }
>
> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
> index 25c571f..7af1480 100644
> --- a/tools/perf/util/map.c
> +++ b/tools/perf/util/map.c
> @@ -454,6 +454,20 @@ void map_groups__exit(struct map_groups *mg)
> }
> }
>
> +bool map_groups__empty(struct map_groups *mg)
> +{
> + int i;
> +
> + for (i = 0; i < MAP__NR_TYPES; ++i) {
> + if (maps__first(&mg->maps[i]))
> + return false;
> + if (!list_empty(&mg->removed_maps[i]))
> + return false;
> + }
> +
> + return true;
> +}
> +
> struct map_groups *map_groups__new(void)
> {
> struct map_groups *mg = malloc(sizeof(*mg));
> diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
> index 7758c72..5806a90 100644
> --- a/tools/perf/util/map.h
> +++ b/tools/perf/util/map.h
> @@ -66,6 +66,7 @@ struct map_groups {
>
> struct map_groups *map_groups__new(void);
> void map_groups__delete(struct map_groups *mg);
> +bool map_groups__empty(struct map_groups *mg);
>
> static inline struct map_groups *map_groups__get(struct map_groups *mg)
> {
> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
> index 7a32f44..ca94295 100644
> --- a/tools/perf/util/thread.c
> +++ b/tools/perf/util/thread.c
> @@ -24,6 +24,41 @@ int thread__init_map_groups(struct thread *thread, struct machine *machine)
> return thread->mg ? 0 : -1;
> }
>
> +int thread__join_map_groups(struct thread *thread, struct machine *machine)
> +{
> + struct thread *leader;
> + pid_t pid = thread->pid_;
> +
> + if (pid == thread->tid)
> + return 0;
> +
> + leader = machine__findnew_thread(machine, pid, pid);
> + if (!leader)
> + return -ENOMEM;
> +
> + if (!leader->mg)
> + leader->mg = map_groups__new();
> +
> + if (!leader->mg)
> + return -ENOMEM;
> +
> + if (thread->mg) {
> + /*
> + * Maps are created from MMAP events which provide the pid and
> + * tid. Consequently there never should be any maps on a thread
> + * with an unknown pid. Just print an error if there are.
> + */
> + if (!map_groups__empty(thread->mg))
> + pr_err("Discarding thread maps for %d:%d\n",
> + thread->pid_, thread->tid);
Because there is nothing in this function (thread__join_map_groups),
checking if it is operating on a thread that has an unknown pid.
So, please consider merging this and its sole caller,
machine__update_thread_pid, so that the test is in the same function as
the assumption that it is operating on a thread with an unknown pid.
Continuing to look at the other patches...
> + map_groups__delete(thread->mg);
> + }
> +
> + thread->mg = map_groups__get(leader->mg);
> +
> + return 0;
> +}
> +
> struct thread *thread__new(pid_t pid, pid_t tid)
> {
> char *comm_str;
> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
> index 3c0c272..9de0629 100644
> --- a/tools/perf/util/thread.h
> +++ b/tools/perf/util/thread.h
> @@ -31,6 +31,7 @@ struct comm;
>
> struct thread *thread__new(pid_t pid, pid_t tid);
> int thread__init_map_groups(struct thread *thread, struct machine *machine);
> +int thread__join_map_groups(struct thread *thread, struct machine *machine);
> void thread__delete(struct thread *thread);
> static inline void thread__exited(struct thread *thread)
> {
> --
> 1.8.3.2
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