NAME
  trace - show or dump the tracing info

SYNOPSIS
  trace [ <show [-c <cpulist>] [-f [no]<flagname>]> | <dump [-sm] <dest-dir>> ]

DESCRIPTION
trace
    shows the current tracer and other informations.

trace show [ -c <cpulist> ] [ -f [no]<flagename> ]
    shows all events with readability text(sorted by timestamp)
    -c: only shows specified CPUs' events.
        ex. trace show -c 1,2    - only shows cpu#1 and cpu#2 's events.
            trace show -c 0,2-7  - only shows cpu#0, cpu#2...cpu#7's events.
    -f: set or clear a flag
        available flags            default
        context_info               true
        sym_offset                 false
        sym_addr                   false
        graph_print_duration       true
        graph_print_overhead       true
        graph_print_abstime        false
        graph_print_cpu            true
        graph_print_proc           false
        graph_print_overrun        false

trace dump [-sm] <dest-dir>
    dump ring_buffers to dest-dir. Then you can parse it
    by other tracing tools. The dirs and files are generated
    the same as debugfs/tracing.
    -m: also dump metadata of ftrace.
    -s: also dump symbols of the kernel <not implemented>.


EXAMPLE, dump ring_buffer:

crash> trace dump -m dumped_tracing
(quit crash)
# ls -R dumped_tracing
dumped_tracing:
events  per_cpu  saved_cmdlines

dumped_tracing/events:
block  ftrace  irq  kmem  sched  skb  workqueue

dumped_tracing/events/block:
block_bio_backmerge  block_bio_frontmerge  block_plug      block_rq_complete  block_rq_requeue  block_unplug_io
block_bio_bounce     block_bio_queue       block_remap     block_rq_insert    block_sleeprq     block_unplug_timer
block_bio_complete   block_getrq           block_rq_abort  block_rq_issue     block_split

dumped_tracing/events/block/block_bio_backmerge:
format

dumped_tracing/events/block/block_bio_bounce:
format
....
dumped_tracing/per_cpu:
cpu0  cpu1

dumped_tracing/per_cpu/cpu0:
trace_pipe_raw

dumped_tracing/per_cpu/cpu1:
trace_pipe_raw


EXAMPLE, shows function tracer 
crash> trace show
           <...>-3677  [001]  6094.628402: pick_next_task_fair <-schedule
           <...>-3677  [001]  6094.628403: pick_next_task_rt <-schedule
           <...>-3677  [001]  6094.628404: pick_next_task_fair <-schedule
           <...>-3677  [001]  6094.628405: pick_next_task_idle <-schedule
           <...>-3677  [001]  6094.628406: calc_load_account_active <-pick_next_task_idle
           <...>-3677  [001]  6094.628407: perf_counter_task_sched_out <-schedule
       <swapper>-0     [001]  6094.628437: finish_task_switch <-schedule
       <swapper>-0     [001]  6094.628438: perf_counter_task_sched_in <-finish_task_switch
       <swapper>-0     [001]  6094.628439: _spin_unlock_irq <-finish_task_switch
       <swapper>-0     [001]  6094.628440: kretprobe_table_lock_ptr <-kretprobe_table_lock
       <swapper>-0     [001]  6094.628442: _spin_lock_irqsave <-kretprobe_table_lock
....
            bash-3580  [000]  6119.756585: native_apic_mem_read <-default_get_apic_id
            bash-3580  [000]  6119.756616: crash_save_cpu <-native_machine_crash_shutdown
            bash-3580  [000]  6119.756687: append_elf_note <-crash_save_cpu
            bash-3580  [000]  6119.756688: strlen <-append_elf_note
            bash-3580  [000]  6119.756712: final_note <-crash_save_cpu
            bash-3580  [000]  6119.756776: machine_kexec <-crash_kexec
            bash-3580  [000]  6119.756824: page_address <-machine_kexec

EXAMPLE, shows function_graph tracer
crash> trace show
 1)   1.187 us    |            }
 1)               |            hrtimer_forward() {
 1)   1.018 us    |              ktime_add_safe();
 1)   0.953 us    |              ktime_add_safe();
 1)   5.419 us    |            }
 1) + 87.322 us   |          }
 1)   1.028 us    |          _spin_lock();
 1)   1.779 us    |          enqueue_hrtimer();
 1) ! 100.743 us  |        }
 1)   1.043 us    |        _spin_unlock();
 1)               |        tick_program_event() {
 1)               |          tick_dev_program_event() {
 1)   1.148 us    |            ktime_get();

EXAMPLE, shows various events
crash> trace show
       <swapper>-0     [001]  9349.585217: softirq_exit: vec=1
       <swapper>-0     [001]  9349.585218: softirq_entry: vec=8
       <swapper>-0     [001]  9349.585226: kmem_cache_free: call_site=c015a221 ptr=0xcfb16200
       <swapper>-0     [001]  9349.585228: kmem_cache_free: call_site=c0151c32 ptr=0xcfb438c0
       <swapper>-0     [001]  9349.585230: sched_process_free: task dhclient-script:3749 [120]
       <swapper>-0     [001]  9349.585237: kfree: call_site=c017f13a ptr=(nil)
       <swapper>-0     [001]  9349.585239: kmem_cache_free: call_site=c013b8f1 ptr=0xcf056ed0
       <swapper>-0     [001]  9349.585241: softirq_exit: vec=8
           <...>-3752  [000]  9349.585717: kmem_cache_alloc: call_site=c01b6a34 ptr=0xcf2c50b0 bytes_req=88 bytes_alloc=88 gfp_flags=80d0
           <...>-3752  [000]  9349.585732: kmem_cache_alloc: call_site=c01b95fa ptr=0xcf2c61e0 bytes_req=12 bytes_alloc=16 gfp_flags=d0