perf sched: Don't read all tracepoint variables in advance
Do it just at the actual consumer of these fields, that way we avoid
needless lookups:
[root@sandy ~]# perf sched record sleep 30s
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 8.585 MB perf.data (~375063 samples) ]
Before:
[root@sandy ~]# perf stat -r 10 perf sched lat > /dev/null
Performance counter stats for 'perf sched lat' (10 runs):
103.592215 task-clock # 0.993 CPUs utilized ( +- 0.33% )
12 context-switches # 0.114 K/sec ( +- 3.29% )
0 cpu-migrations # 0.000 K/sec
7,605 page-faults # 0.073 M/sec ( +- 0.00% )
345,796,112 cycles # 3.338 GHz ( +- 0.07% ) [82.90%]
106,876,796 stalled-cycles-frontend # 30.91% frontend cycles idle ( +- 0.38% ) [83.23%]
62,060,877 stalled-cycles-backend # 17.95% backend cycles idle ( +- 0.80% ) [67.14%]
628,246,586 instructions # 1.82 insns per cycle
# 0.17 stalled cycles per insn ( +- 0.04% ) [83.64%]
134,962,057 branches # 1302.820 M/sec ( +- 0.10% ) [83.64%]
1,233,037 branch-misses # 0.91% of all branches ( +- 0.29% ) [83.41%]
0.104333272 seconds time elapsed ( +- 0.33% )
[root@sandy ~]# perf stat -r 10 perf sched lat > /dev/null
Performance counter stats for 'perf sched lat' (10 runs):
98.848272 task-clock # 0.993 CPUs utilized ( +- 0.48% )
11 context-switches # 0.112 K/sec ( +- 2.83% )
0 cpu-migrations # 0.003 K/sec ( +- 50.92% )
7,604 page-faults # 0.077 M/sec ( +- 0.00% )
332,216,085 cycles # 3.361 GHz ( +- 0.14% ) [82.87%]
100,623,710 stalled-cycles-frontend # 30.29% frontend cycles idle ( +- 0.53% ) [82.95%]
58,788,692 stalled-cycles-backend # 17.70% backend cycles idle ( +- 0.59% ) [67.15%]
609,402,433 instructions # 1.83 insns per cycle
# 0.17 stalled cycles per insn ( +- 0.04% ) [83.76%]
131,277,138 branches # 1328.067 M/sec ( +- 0.06% ) [83.77%]
1,117,871 branch-misses # 0.85% of all branches ( +- 0.32% ) [83.51%]
0.099580430 seconds time elapsed ( +- 0.48% )
[root@sandy ~]#
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-kracdpw8wqlr0xjh75uk8g11@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
9ec3f4e437