perf tools: Clarify the output of perf sched map.

In output of perf sched map, any shortname of thread will be explained
at the first time when it appear.

Example:
              *A0       228836.978985 secs A0 => perf:23032
          *.   A0       228836.979016 secs B0 => swapper:0
           .  *C0       228836.979099 secs C0 => migration/3:22
  *A0      .   C0       228836.979115 secs
   A0      .  *.        228836.979115 secs

But B0, which is explained as swapper:0 did not appear in the
left part of output. Instead, we use '.' as the shortname of
swapper:0. So the comment of "B0 => swapper:0" is not easy to
understand.

This patch clarify the output of perf sched map with not allocating
one letter-number shortname for swapper:0 and print ". => swapper:0"
as the explanation for swapper:0.

Example:
              *A0       228836.978985 secs A0 => perf:23032
          * .  A0       228836.979016 secs .  => swapper:0
            . *B0       228836.979099 secs B0 => migration/3:22
  *A0       .  B0       228836.979115 secs
   A0       . * .       228836.979115 secs
   A0     *C0   .       228836.979225 secs C0 => ksoftirqd/2:18
   A0     *D0   .       228836.979236 secs D0 => rcu_sched:7

Signed-off-by: Dongsheng <yangds.fnst@cn.fujitsu.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/1399354741-19522-1-git-send-email-yangds.fnst@cn.fujitsu.com
[ small style fixes to make checkpatch happy ]
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

1 files changed, 20 insertions, 15 deletions

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 4f0dd21b5923..2579215f5743 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1300,17 +1300,25 @@ static int map_switch_event(struct perf_sched *sched, struct perf_evsel *evsel,
 
         new_shortname = 0;
         if (!sched_in->shortname[0]) {
-                sched_in->shortname[0] = sched->next_shortname1;
-                sched_in->shortname[1] = sched->next_shortname2;
-
-                if (sched->next_shortname1 < 'Z') {
-                        sched->next_shortname1++;
+                if (!strcmp(thread__comm_str(sched_in), "swapper")) {
+                        /*
+                         * Don't allocate a letter-number for swapper:0
+                         * as a shortname. Instead, we use '.' for it.
+                         */
+                        sched_in->shortname[0] = '.';
+                        sched_in->shortname[1] = ' ';
                 } else {
-                        sched->next_shortname1='A';
-                        if (sched->next_shortname2 < '9') {
-                                sched->next_shortname2++;
+                        sched_in->shortname[0] = sched->next_shortname1;
+                        sched_in->shortname[1] = sched->next_shortname2;
+
+                        if (sched->next_shortname1 < 'Z') {
+                                sched->next_shortname1++;
                         } else {
-                                sched->next_shortname2='0';
+                                sched->next_shortname1 = 'A';
+                                if (sched->next_shortname2 < '9')
+                                        sched->next_shortname2++;
+                                else
+                                        sched->next_shortname2 = '0';
                         }
                 }
                 new_shortname = 1;
@@ -1322,12 +1330,9 @@ static int map_switch_event(struct perf_sched *sched, struct perf_evsel *evsel,
                 else
                         printf("*");
 
-                if (sched->curr_thread[cpu]) {
-                        if (sched->curr_thread[cpu]->tid)
-                                printf("%2s ", sched->curr_thread[cpu]->shortname);
-                        else
-                                printf(".  ");
-                } else
+                if (sched->curr_thread[cpu])
+                        printf("%2s ", sched->curr_thread[cpu]->shortname);
+                else
                         printf("   ");
         }