cc5fc8bfc9
Now that stacktraces can be part of synthetic events, allow a key to be
typed as a stacktrace.
# cd /sys/kernel/tracing
# echo 's:block_lat u64 delta; unsigned long stack[];' >> dynamic_events
# echo 'hist:keys=next_pid:ts=common_timestamp.usecs,st=stacktrace if prev_state == 2' >> events/sched/sched_switch/trigger
# echo 'hist:keys=prev_pid:delta=common_timestamp.usecs-$ts,st2=$st:onmatch(sched.sched_switch).trace(block_lat,$delta,$st2)' >> events/sched/sched_switch/trigger
# echo 'hist:keys=delta.buckets=100,stack.stacktrace:sort=delta' > events/synthetic/block_lat/trigger
# cat events/synthetic/block_lat/hist
# event histogram
#
# trigger info: hist:keys=delta.buckets=100,stacktrace:vals=hitcount:sort=delta.buckets=100:size=2048 [active]
#
{ delta: ~ 0-99, stacktrace:
event_hist_trigger+0x464/0x480
event_triggers_call+0x52/0xe0
trace_event_buffer_commit+0x193/0x250
trace_event_raw_event_sched_switch+0xfc/0x150
__traceiter_sched_switch+0x41/0x60
__schedule+0x448/0x7b0
schedule_idle+0x26/0x40
cpu_startup_entry+0x19/0x20
start_secondary+0xed/0xf0
secondary_startup_64_no_verify+0xe0/0xeb
} hitcount: 6
{ delta: ~ 0-99, stacktrace:
event_hist_trigger+0x464/0x480
event_triggers_call+0x52/0xe0
trace_event_buffer_commit+0x193/0x250
trace_event_raw_event_sched_switch+0xfc/0x150
__traceiter_sched_switch+0x41/0x60
__schedule+0x448/0x7b0
schedule_idle+0x26/0x40
cpu_startup_entry+0x19/0x20
__pfx_kernel_init+0x0/0x10
arch_call_rest_init+0xa/0x24
start_kernel+0x964/0x98d
secondary_startup_64_no_verify+0xe0/0xeb
} hitcount: 3
{ delta: ~ 0-99, stacktrace:
event_hist_trigger+0x464/0x480
event_triggers_call+0x52/0xe0
trace_event_buffer_commit+0x193/0x250
trace_event_raw_event_sched_switch+0xfc/0x150
__traceiter_sched_switch+0x41/0x60
__schedule+0x448/0x7b0
schedule+0x5a/0xb0
worker_thread+0xaf/0x380
kthread+0xe9/0x110
ret_from_fork+0x2c/0x50
} hitcount: 1
{ delta: ~ 100-199, stacktrace:
event_hist_trigger+0x464/0x480
event_triggers_call+0x52/0xe0
trace_event_buffer_commit+0x193/0x250
trace_event_raw_event_sched_switch+0xfc/0x150
__traceiter_sched_switch+0x41/0x60
__schedule+0x448/0x7b0
schedule_idle+0x26/0x40
cpu_startup_entry+0x19/0x20
start_secondary+0xed/0xf0
secondary_startup_64_no_verify+0xe0/0xeb
} hitcount: 15
[..]
{ delta: ~ 8500-8599, stacktrace:
event_hist_trigger+0x464/0x480
event_triggers_call+0x52/0xe0
trace_event_buffer_commit+0x193/0x250
trace_event_raw_event_sched_switch+0xfc/0x150
__traceiter_sched_switch+0x41/0x60
__schedule+0x448/0x7b0
schedule_idle+0x26/0x40
cpu_startup_entry+0x19/0x20
start_secondary+0xed/0xf0
secondary_startup_64_no_verify+0xe0/0xeb
} hitcount: 1
Totals:
Hits: 89
Entries: 11
Dropped: 0
Link: https://lkml.kernel.org/r/20230117152236.167046397@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Ching-lin Yu <chinglinyu@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.