perf events: Change perf parameter --pid to process-wide collection instead of thread-wide

Parameter --pid (or -p) of perf currently means a thread-wide
collection. For exmaple, if a process whose id is 8888 has 10
threads, 'perf top -p 8888' just collects the main thread
statistics. That's misleading. Users are used to attach a whole
process when debugging a process by gdb. To follow normal usage
style, the patch change --pid to process-wide collection and add
--tid (-t) to mean a thread-wide collection.

Usage example is:

 # perf top -p 8888
 # perf record -p 8888 -f sleep 10
 # perf stat -p 8888 -f sleep 10

Above commands collect the statistics of all threads of process
8888.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sheng Yang <sheng@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jes Sorensen <Jes.Sorensen@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: zhiteng.huang@intel.com
Cc: Zachary Amsden <zamsden@redhat.com>
LKML-Reference: <1268922965-14774-3-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 33 insertions, 0 deletions

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index fa968312ee7d..ea6506234d57 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -7,6 +7,37 @@
 #include "util.h"
 #include "debug.h"
 
+int find_all_tid(int pid, pid_t ** all_tid)
+{
+	char name[256];
+	int items;
+	struct dirent **namelist = NULL;
+	int ret = 0;
+	int i;
+
+	sprintf(name, "/proc/%d/task", pid);
+	items = scandir(name, &namelist, NULL, NULL);
+	if (items <= 0)
+                return -ENOENT;
+	*all_tid = malloc(sizeof(pid_t) * items);
+	if (!*all_tid) {
+		ret = -ENOMEM;
+		goto failure;
+	}
+
+	for (i = 0; i < items; i++)
+		(*all_tid)[i] = atoi(namelist[i]->d_name);
+
+	ret = items;
+
+failure:
+	for (i=0; i<items; i++)
+		free(namelist[i]);
+	free(namelist);
+
+	return ret;
+}
+
 void map_groups__init(struct map_groups *self)
 {
 	int i;
@@ -348,3 +379,4 @@ struct symbol *map_groups__find_symbol(struct map_groups *self,
 
 	return NULL;
 }
+
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index dcf70303e58e..a81426a891bf 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -23,6 +23,7 @@ struct thread {
 	int			comm_len;
 };
 
+int find_all_tid(int pid, pid_t ** all_tid);
 void map_groups__init(struct map_groups *self);
 int thread__set_comm(struct thread *self, const char *comm);
 int thread__comm_len(struct thread *self);