[PATCH 19/20] perf tools: Reference count struct thread
From: Arnaldo Carvalho de Melo
Date: Mon Mar 02 2015 - 22:27:36 EST
From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
We need to do that to stop accumulating entries in the dead_threads
linked list, i.e. we were keeping references to threads in struct hists
that continue to exist even after a thread exited and was removed from
the machine threads rbtree.
We still keep the dead_threads list, but just for debugging, allowing us
to iterate at any given point over the threads that still are referenced
by things like struct hist_entry.
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-3ejvfyed0r7ue61dkurzjux4@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-sched.c | 2 +-
tools/perf/builtin-trace.c | 7 ++++++-
tools/perf/ui/browsers/hists.c | 6 +++---
tools/perf/util/build-id.c | 5 +++--
tools/perf/util/hist.c | 2 ++
tools/perf/util/hist.h | 2 +-
tools/perf/util/machine.c | 44 ++++++++++++++++++++++--------------------
tools/perf/util/machine.h | 1 -
tools/perf/util/session.c | 6 ------
tools/perf/util/thread.c | 14 ++++++++++++++
tools/perf/util/thread.h | 13 +++++++++++++
11 files changed, 66 insertions(+), 36 deletions(-)
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 7ce296618717..e00e2eaf89da 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -831,7 +831,7 @@ static int thread_atoms_insert(struct perf_sched *sched, struct thread *thread)
return -1;
}
- atoms->thread = thread;
+ atoms->thread = thread__get(thread);
INIT_LIST_HEAD(&atoms->work_list);
__thread_latency_insert(&sched->atom_root, atoms, &sched->cmp_pid);
return 0;
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index d95a8f4d988c..211614fba217 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1741,7 +1741,10 @@ static int trace__sys_enter(struct trace *trace, struct perf_evsel *evsel,
} else
ttrace->entry_pending = true;
- trace->current = thread;
+ if (trace->current != thread) {
+ thread__put(trace->current);
+ trace->current = thread__get(thread);
+ }
return 0;
}
@@ -2274,6 +2277,8 @@ next_event:
}
out_disable:
+ thread__zput(trace->current);
+
perf_evlist__disable(evlist);
if (!err) {
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 788506eef567..ad312d91caed 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -1467,7 +1467,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
perf_hpp__set_user_width(symbol_conf.col_width_list_str);
while (1) {
- const struct thread *thread = NULL;
+ struct thread *thread = NULL;
const struct dso *dso = NULL;
int choice = 0,
annotate = -2, zoom_dso = -2, zoom_thread = -2,
@@ -1754,13 +1754,13 @@ zoom_thread:
pstack__remove(fstack, &browser->hists->thread_filter);
zoom_out_thread:
ui_helpline__pop();
- browser->hists->thread_filter = NULL;
+ thread__zput(browser->hists->thread_filter);
perf_hpp__set_elide(HISTC_THREAD, false);
} else {
ui_helpline__fpush("To zoom out press <- or -> + \"Zoom out of %s(%d) thread\"",
thread->comm_set ? thread__comm_str(thread) : "",
thread->tid);
- browser->hists->thread_filter = thread;
+ browser->hists->thread_filter = thread__get(thread);
perf_hpp__set_elide(HISTC_THREAD, false);
pstack__push(fstack, &browser->hists->thread_filter);
}
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index ffdc338df925..a19674666b4e 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -61,8 +61,9 @@ static int perf_event__exit_del_thread(struct perf_tool *tool __maybe_unused,
if (thread) {
rb_erase(&thread->rb_node, &machine->threads);
- machine->last_match = NULL;
- thread__delete(thread);
+ if (machine->last_match == thread)
+ thread__zput(machine->last_match);
+ thread__put(thread);
}
return 0;
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 70b48a65064c..95f5ab707b74 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -355,6 +355,7 @@ static struct hist_entry *hist_entry__new(struct hist_entry *template,
callchain_init(he->callchain);
INIT_LIST_HEAD(&he->pairs.node);
+ thread__get(he->thread);
}
return he;
@@ -941,6 +942,7 @@ hist_entry__collapse(struct hist_entry *left, struct hist_entry *right)
void hist_entry__delete(struct hist_entry *he)
{
+ thread__zput(he->thread);
zfree(&he->branch_info);
zfree(&he->mem_info);
zfree(&he->stat_acc);
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 2b690d028907..e988c9fcd1bc 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -60,7 +60,7 @@ struct hists {
struct rb_root entries_collapsed;
u64 nr_entries;
u64 nr_non_filtered_entries;
- const struct thread *thread_filter;
+ struct thread *thread_filter;
const struct dso *dso_filter;
const char *uid_filter_str;
const char *symbol_filter_str;
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 9e0f60a7e7b3..24f8c978cfd4 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -14,6 +14,8 @@
#include "unwind.h"
#include "linux/hash.h"
+static void machine__remove_thread(struct machine *machine, struct thread *th);
+
static void dsos__init(struct dsos *dsos)
{
INIT_LIST_HEAD(&dsos->head);
@@ -89,16 +91,6 @@ static void dsos__delete(struct dsos *dsos)
}
}
-void machine__delete_dead_threads(struct machine *machine)
-{
- struct thread *n, *t;
-
- list_for_each_entry_safe(t, n, &machine->dead_threads, node) {
- list_del(&t->node);
- thread__delete(t);
- }
-}
-
void machine__delete_threads(struct machine *machine)
{
struct rb_node *nd = rb_first(&machine->threads);
@@ -106,9 +98,8 @@ void machine__delete_threads(struct machine *machine)
while (nd) {
struct thread *t = rb_entry(nd, struct thread, rb_node);
- rb_erase(&t->rb_node, &machine->threads);
nd = rb_next(nd);
- thread__delete(t);
+ machine__remove_thread(machine, t);
}
}
@@ -361,9 +352,13 @@ static struct thread *__machine__findnew_thread(struct machine *machine,
* the full rbtree:
*/
th = machine->last_match;
- if (th && th->tid == tid) {
- machine__update_thread_pid(machine, th, pid);
- return th;
+ if (th != NULL) {
+ if (th->tid == tid) {
+ machine__update_thread_pid(machine, th, pid);
+ return th;
+ }
+
+ thread__zput(machine->last_match);
}
while (*p != NULL) {
@@ -371,7 +366,7 @@ static struct thread *__machine__findnew_thread(struct machine *machine,
th = rb_entry(parent, struct thread, rb_node);
if (th->tid == tid) {
- machine->last_match = th;
+ machine->last_match = thread__get(th);
machine__update_thread_pid(machine, th, pid);
return th;
}
@@ -403,8 +398,11 @@ static struct thread *__machine__findnew_thread(struct machine *machine,
thread__delete(th);
return NULL;
}
-
- machine->last_match = th;
+ /*
+ * It is now in the rbtree, get a ref
+ */
+ thread__get(th);
+ machine->last_match = thread__get(th);
}
return th;
@@ -1238,13 +1236,17 @@ out_problem:
static void machine__remove_thread(struct machine *machine, struct thread *th)
{
- machine->last_match = NULL;
+ if (machine->last_match == th)
+ thread__zput(machine->last_match);
+
rb_erase(&th->rb_node, &machine->threads);
/*
- * We may have references to this thread, for instance in some hist_entry
- * instances, so just move them to a separate list.
+ * Move it first to the dead_threads list, then drop the reference,
+ * if this is the last reference, then the thread__delete destructor
+ * will be called and we will remove it from the dead_threads list.
*/
list_add_tail(&th->node, &machine->dead_threads);
+ thread__put(th);
}
int machine__process_fork_event(struct machine *machine, union perf_event *event,
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index e8b7779a0a3f..e2faf3b47e7b 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -118,7 +118,6 @@ void machines__set_comm_exec(struct machines *machines, bool comm_exec);
struct machine *machine__new_host(void);
int machine__init(struct machine *machine, const char *root_dir, pid_t pid);
void machine__exit(struct machine *machine);
-void machine__delete_dead_threads(struct machine *machine);
void machine__delete_threads(struct machine *machine);
void machine__delete(struct machine *machine);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index e4f166981ff0..ed4e5cf2bd9d 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -138,11 +138,6 @@ struct perf_session *perf_session__new(struct perf_data_file *file,
return NULL;
}
-static void perf_session__delete_dead_threads(struct perf_session *session)
-{
- machine__delete_dead_threads(&session->machines.host);
-}
-
static void perf_session__delete_threads(struct perf_session *session)
{
machine__delete_threads(&session->machines.host);
@@ -167,7 +162,6 @@ static void perf_session_env__delete(struct perf_session_env *env)
void perf_session__delete(struct perf_session *session)
{
perf_session__destroy_kernel_maps(session);
- perf_session__delete_dead_threads(session);
perf_session__delete_threads(session);
perf_session_env__delete(&session->header.env);
machines__exit(&session->machines);
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 9ebc8b1f9be5..a5dbba95107f 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -82,6 +82,20 @@ void thread__delete(struct thread *thread)
free(thread);
}
+struct thread *thread__get(struct thread *thread)
+{
+ ++thread->refcnt;
+ return thread;
+}
+
+void thread__put(struct thread *thread)
+{
+ if (thread && --thread->refcnt == 0) {
+ list_del_init(&thread->node);
+ thread__delete(thread);
+ }
+}
+
struct comm *thread__comm(const struct thread *thread)
{
if (list_empty(&thread->comm_list))
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 160fd066a7d1..783b6688d2f7 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -20,6 +20,7 @@ struct thread {
pid_t tid;
pid_t ppid;
int cpu;
+ int refcnt;
char shortname[3];
bool comm_set;
bool dead; /* if set thread has exited */
@@ -37,6 +38,18 @@ struct comm;
struct thread *thread__new(pid_t pid, pid_t tid);
int thread__init_map_groups(struct thread *thread, struct machine *machine);
void thread__delete(struct thread *thread);
+
+struct thread *thread__get(struct thread *thread);
+void thread__put(struct thread *thread);
+
+static inline void __thread__zput(struct thread **thread)
+{
+ thread__put(*thread);
+ *thread = NULL;
+}
+
+#define thread__zput(thread) __thread__zput(&thread)
+
static inline void thread__exited(struct thread *thread)
{
thread->dead = true;
--
1.9.3
--
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