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>

1 files changed, 75 insertions, 35 deletions

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 5f41244cbbf2..c92f90ff5a9f 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -46,6 +46,7 @@
 #include "util/debug.h"
 #include "util/header.h"
 #include "util/cpumap.h"
+#include "util/thread.h"
 
 #include <sys/prctl.h>
 #include <math.h>
@@ -74,10 +75,13 @@ static int			run_count			=  1;
 static int                      inherit                         =  1;
 static int                      scale                           =  1;
 static pid_t                    target_pid                      = -1;
+static pid_t                    target_tid                      = -1;
+static pid_t                    *all_tids                       =  NULL;
+static int                      thread_num                      =  0;
 static pid_t                    child_pid                       = -1;
 static int                      null_run                        =  0;
 
-static int                      fd[MAX_NR_CPUS][MAX_COUNTERS];
+static int                      *fd[MAX_NR_CPUS][MAX_COUNTERS];
 
 static int                      event_scaled[MAX_COUNTERS];
 
@@ -140,9 +144,10 @@ struct stats			runtime_branches_stats;
 #define ERR_PERF_OPEN \
 "Error: counter %d, sys_perf_event_open() syscall returned with %d (%s)\n"
 
-static void create_perf_stat_counter(int counter, int pid)
+static void create_perf_stat_counter(int counter)
 {
         struct perf_event_attr *attr = attrs + counter;
+        int thread;
 
         if (scale)
                 attr->read_format = PERF_FORMAT_TOTAL_TIME_ENABLED |
@@ -152,10 +157,11 @@ static void create_perf_stat_counter(int counter, int pid)
                 unsigned int cpu;
 
                 for (cpu = 0; cpu < nr_cpus; cpu++) {
-                        fd[cpu][counter] = sys_perf_event_open(attr, -1, cpumap[cpu], -1, 0);
-                        if (fd[cpu][counter] < 0 && verbose)
+                        fd[cpu][counter][0] = sys_perf_event_open(attr,
+                                        -1, cpumap[cpu], -1, 0);
+                        if (fd[cpu][counter][0] < 0 && verbose)
                                 fprintf(stderr, ERR_PERF_OPEN, counter,
-                                        fd[cpu][counter], strerror(errno));
+                                        fd[cpu][counter][0], strerror(errno));
                 }
         } else {
                 attr->inherit        = inherit;
@@ -163,11 +169,14 @@ static void create_perf_stat_counter(int counter, int pid)
                         attr->disabled = 1;
                         attr->enable_on_exec = 1;
                 }
-
-                fd[0][counter] = sys_perf_event_open(attr, pid, -1, -1, 0);
-                if (fd[0][counter] < 0 && verbose)
-                        fprintf(stderr, ERR_PERF_OPEN, counter,
-                                fd[0][counter], strerror(errno));
+                for (thread = 0; thread < thread_num; thread++) {
+                        fd[0][counter][thread] = sys_perf_event_open(attr,
+                                all_tids[thread], -1, -1, 0);
+                        if (fd[0][counter][thread] < 0 && verbose)
+                                fprintf(stderr, ERR_PERF_OPEN, counter,
+                                        fd[0][counter][thread],
+                                        strerror(errno));
+                }
         }
 }
 
@@ -192,25 +201,28 @@ static void read_counter(int counter)
         unsigned int cpu;
         size_t res, nv;
         int scaled;
-        int i;
+        int i, thread;
 
         count[0] = count[1] = count[2] = 0;
 
         nv = scale ? 3 : 1;
         for (cpu = 0; cpu < nr_cpus; cpu++) {
-                if (fd[cpu][counter] < 0)
-                        continue;
-
-                res = read(fd[cpu][counter], single_count, nv * sizeof(u64));
-                assert(res == nv * sizeof(u64));
-
-                close(fd[cpu][counter]);
-                fd[cpu][counter] = -1;
-
-                count[0] += single_count[0];
-                if (scale) {
-                        count[1] += single_count[1];
-                        count[2] += single_count[2];
+                for (thread = 0; thread < thread_num; thread++) {
+                        if (fd[cpu][counter][thread] < 0)
+                                continue;
+
+                        res = read(fd[cpu][counter][thread],
+                                        single_count, nv * sizeof(u64));
+                        assert(res == nv * sizeof(u64));
+
+                        close(fd[cpu][counter][thread]);
+                        fd[cpu][counter][thread] = -1;
+
+                        count[0] += single_count[0];
+                        if (scale) {
+                                count[1] += single_count[1];
+                                count[2] += single_count[2];
+                        }
                 }
         }
 
@@ -253,7 +265,6 @@ static int run_perf_stat(int argc __used, const char **argv)
         unsigned long long t0, t1;
         int status = 0;
         int counter;
-        int pid;
         int child_ready_pipe[2], go_pipe[2];
         const bool forks = (argc > 0);
         char buf;
@@ -299,6 +310,9 @@ static int run_perf_stat(int argc __used, const char **argv)
                         exit(-1);
                 }
 
+                if (target_tid == -1 && target_pid == -1 && !system_wide)
+                        all_tids[0] = child_pid;
+
                 /*
                  * Wait for the child to be ready to exec.
                  */
@@ -309,12 +323,8 @@ static int run_perf_stat(int argc __used, const char **argv)
                 close(child_ready_pipe[0]);
         }
 
-        if (target_pid == -1)
-                pid = child_pid;
-        else
-                pid = target_pid;
         for (counter = 0; counter < nr_counters; counter++)
-                create_perf_stat_counter(counter, pid);
+                create_perf_stat_counter(counter);
 
         /*
          * Enable counters and exec the command:
@@ -433,12 +443,14 @@ static void print_stat(int argc, const char **argv)
 
         fprintf(stderr, "\n");
         fprintf(stderr, " Performance counter stats for ");
-        if(target_pid == -1) {
+        if(target_pid == -1 && target_tid == -1) {
                 fprintf(stderr, "\'%s", argv[0]);
                 for (i = 1; i < argc; i++)
                         fprintf(stderr, " %s", argv[i]);
-        }else
-                fprintf(stderr, "task pid \'%d", target_pid);
+        } else if (target_pid != -1)
+                fprintf(stderr, "process id \'%d", target_pid);
+        else
+                fprintf(stderr, "thread id \'%d", target_tid);
 
         fprintf(stderr, "\'");
         if (run_count > 1)
@@ -493,7 +505,9 @@ static const struct option options[] = {
         OPT_BOOLEAN('i', "inherit", &inherit,
                     "child tasks inherit counters"),
         OPT_INTEGER('p', "pid", &target_pid,
-                    "stat events on existing pid"),
+                    "stat events on existing process id"),
+        OPT_INTEGER('t', "tid", &target_tid,
+                    "stat events on existing thread id"),
         OPT_BOOLEAN('a', "all-cpus", &system_wide,
                     "system-wide collection from all CPUs"),
         OPT_BOOLEAN('c', "scale", &scale,
@@ -510,10 +524,11 @@ static const struct option options[] = {
 int cmd_stat(int argc, const char **argv, const char *prefix __used)
 {
         int status;
+        int i,j;
 
         argc = parse_options(argc, argv, options, stat_usage,
                 PARSE_OPT_STOP_AT_NON_OPTION);
-        if (!argc && target_pid == -1)
+        if (!argc && target_pid == -1 && target_tid == -1)
                 usage_with_options(stat_usage, options);
         if (run_count <= 0)
                 usage_with_options(stat_usage, options);
@@ -529,6 +544,31 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
         else
                 nr_cpus = 1;
 
+        if (target_pid != -1) {
+                target_tid = target_pid;
+                thread_num = find_all_tid(target_pid, &all_tids);
+                if (thread_num <= 0) {
+                        fprintf(stderr, "Can't find all threads of pid %d\n",
+                                        target_pid);
+                        usage_with_options(stat_usage, options);
+                }
+        } else {
+                all_tids=malloc(sizeof(pid_t));
+                if (!all_tids)
+                        return -ENOMEM;
+
+                all_tids[0] = target_tid;
+                thread_num = 1;
+        }
+
+        for (i = 0; i < MAX_NR_CPUS; i++) {
+                for (j = 0; j < MAX_COUNTERS; j++) {
+                        fd[i][j] = malloc(sizeof(int)*thread_num);
+                        if (!fd[i][j])
+                                return -ENOMEM;
+                }
+        }
+
         /*
          * We dont want to block the signals - that would cause
          * child tasks to inherit that and Ctrl-C would not work.