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e302cf3f96
Impact: refactor the branch tracer
This patch adapts the branch tracer to the tracing API.
This is a proof of concept because the branch tracer implements two
"stat tracing" that were split in two files.
So I added an option to the branch tracer: stat_all_branch.
If it is set, then trace_stat will output all of the branches
entries stats. Otherwise, it will print the annotated branches.
Its is a kind of quick trick, waiting for a better solution.
By default, the annotated branches stat are sorted by incorrect branch
prediction percentage.
Ie:
correct incorrect % Function File Line
------- --------- - -------- ---- ----
0 1 100 native_smp_prepare_cpus smpboot.c 1228
0 1 100 hpet_rtc_timer_reinit hpet.c 1057
0 18032 100 sched_info_queued sched_stats.h 223
0 684 100 yield_task_fair sched_fair.c 984
0 282 100 pre_schedule_rt sched_rt.c 1263
0 13414 100 sched_info_dequeued sched_stats.h 178
0 21724 100 sched_info_switch sched_stats.h 270
0 1 100 get_signal_to_deliver signal.c 1820
0 8 100 __cancel_work_timer workqueue.c 560
0 212 100 verify_export_symbols module.c 1509
0 17 100 __rmqueue_fallback page_alloc.c 793
0 43 100 clear_page_mlock internal.h 129
0 124 100 try_to_unmap_anon rmap.c 1021
0 53 100 try_to_unmap_anon rmap.c 1013
0 6 100 vma_address rmap.c 232
0 3301 100 try_to_unmap_file rmap.c 1082
0 466 100 try_to_unmap_file rmap.c 1077
0 1 100 mem_cgroup_create memcontrol.c 1090
0 3 100 inotify_find_update_watch inotify.c 726
2 30163 99 perf_counter_task_sched_out perf_counter.c 385
1 2935 99 percpu_free allocpercpu.c 138
1544 297672 99 dentry_lru_del_init dcache.c 153
8 1074 99 input_pass_event input.c 86
1390 76781 98 mapping_unevictable pagemap.h 50
280 6665 95 pick_next_task_rt sched_rt.c 889
750 4826 86 next_pidmap pid.c 194
2 8 80 blocking_notifier_chain_regist notifier.c 220
36 130 78 ioremap_pte_range ioremap.c 22
1093 3247 74 IS_ERR err.h 34
1023 2908 73 sched_slice sched_fair.c 445
22 60 73 disk_put_part genhd.h 206
[...]
It enables a developer to quickly address the source of incorrect branch
predictions. Note that this sorting would be better with a second sort on
the number of incorrect predictions.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>