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authorSteven Rostedt <srostedt@redhat.com>2011-02-08 13:19:49 -0500
committerSteven Rostedt <rostedt@goodmis.org>2011-02-08 17:14:56 -0500
commit87d80de2800d087ea833cb79bc13f85ff34ed49f (patch)
treeddd0cf19cd3828cfa4c2238e11bc5a0715555da4 /Documentation/trace/ftrace.txt
parentf4d5c029bd6731baac0937324cef0f746e7d5ea7 (diff)
tracing: Remove obsolete sched_switch tracer
The trace events sched_switch and sched_wakeup do the same thing as the stand alone sched_switch tracer does. It is no longer needed. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace/ftrace.txt')
-rw-r--r--Documentation/trace/ftrace.txt110
1 files changed, 0 insertions, 110 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 557c1edecca..65eddb7cfa0 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -202,10 +202,6 @@ Here is the list of current tracers that may be configured.
202 to draw a graph of function calls similar to C code 202 to draw a graph of function calls similar to C code
203 source. 203 source.
204 204
205 "sched_switch"
206
207 Traces the context switches and wakeups between tasks.
208
209 "irqsoff" 205 "irqsoff"
210 206
211 Traces the areas that disable interrupts and saves 207 Traces the areas that disable interrupts and saves
@@ -273,39 +269,6 @@ format, the function name that was traced "path_put" and the
273parent function that called this function "path_walk". The 269parent function that called this function "path_walk". The
274timestamp is the time at which the function was entered. 270timestamp is the time at which the function was entered.
275 271
276The sched_switch tracer also includes tracing of task wakeups
277and context switches.
278
279 ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 2916:115:S
280 ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 10:115:S
281 ksoftirqd/1-7 [01] 1453.070013: 7:115:R ==> 10:115:R
282 events/1-10 [01] 1453.070013: 10:115:S ==> 2916:115:R
283 kondemand/1-2916 [01] 1453.070013: 2916:115:S ==> 7:115:R
284 ksoftirqd/1-7 [01] 1453.070013: 7:115:S ==> 0:140:R
285
286Wake ups are represented by a "+" and the context switches are
287shown as "==>". The format is:
288
289 Context switches:
290
291 Previous task Next Task
292
293 <pid>:<prio>:<state> ==> <pid>:<prio>:<state>
294
295 Wake ups:
296
297 Current task Task waking up
298
299 <pid>:<prio>:<state> + <pid>:<prio>:<state>
300
301The prio is the internal kernel priority, which is the inverse
302of the priority that is usually displayed by user-space tools.
303Zero represents the highest priority (99). Prio 100 starts the
304"nice" priorities with 100 being equal to nice -20 and 139 being
305nice 19. The prio "140" is reserved for the idle task which is
306the lowest priority thread (pid 0).
307
308
309Latency trace format 272Latency trace format
310-------------------- 273--------------------
311 274
@@ -491,79 +454,6 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
491 latencies, as described in "Latency 454 latencies, as described in "Latency
492 trace format". 455 trace format".
493 456
494sched_switch
495------------
496
497This tracer simply records schedule switches. Here is an example
498of how to use it.
499
500 # echo sched_switch > current_tracer
501 # echo 1 > tracing_enabled
502 # sleep 1
503 # echo 0 > tracing_enabled
504 # cat trace
505
506# tracer: sched_switch
507#
508# TASK-PID CPU# TIMESTAMP FUNCTION
509# | | | | |
510 bash-3997 [01] 240.132281: 3997:120:R + 4055:120:R
511 bash-3997 [01] 240.132284: 3997:120:R ==> 4055:120:R
512 sleep-4055 [01] 240.132371: 4055:120:S ==> 3997:120:R
513 bash-3997 [01] 240.132454: 3997:120:R + 4055:120:S
514 bash-3997 [01] 240.132457: 3997:120:R ==> 4055:120:R
515 sleep-4055 [01] 240.132460: 4055:120:D ==> 3997:120:R
516 bash-3997 [01] 240.132463: 3997:120:R + 4055:120:D
517 bash-3997 [01] 240.132465: 3997:120:R ==> 4055:120:R
518 <idle>-0 [00] 240.132589: 0:140:R + 4:115:S
519 <idle>-0 [00] 240.132591: 0:140:R ==> 4:115:R
520 ksoftirqd/0-4 [00] 240.132595: 4:115:S ==> 0:140:R
521 <idle>-0 [00] 240.132598: 0:140:R + 4:115:S
522 <idle>-0 [00] 240.132599: 0:140:R ==> 4:115:R
523 ksoftirqd/0-4 [00] 240.132603: 4:115:S ==> 0:140:R
524 sleep-4055 [01] 240.133058: 4055:120:S ==> 3997:120:R
525 [...]
526
527
528As we have discussed previously about this format, the header
529shows the name of the trace and points to the options. The
530"FUNCTION" is a misnomer since here it represents the wake ups
531and context switches.
532
533The sched_switch file only lists the wake ups (represented with
534'+') and context switches ('==>') with the previous task or
535current task first followed by the next task or task waking up.
536The format for both of these is PID:KERNEL-PRIO:TASK-STATE.
537Remember that the KERNEL-PRIO is the inverse of the actual
538priority with zero (0) being the highest priority and the nice
539values starting at 100 (nice -20). Below is a quick chart to map
540the kernel priority to user land priorities.
541
542 Kernel Space User Space
543 ===============================================================
544 0(high) to 98(low) user RT priority 99(high) to 1(low)
545 with SCHED_RR or SCHED_FIFO
546 ---------------------------------------------------------------
547 99 sched_priority is not used in scheduling
548 decisions(it must be specified as 0)
549 ---------------------------------------------------------------
550 100(high) to 139(low) user nice -20(high) to 19(low)
551 ---------------------------------------------------------------
552 140 idle task priority
553 ---------------------------------------------------------------
554
555The task states are:
556
557 R - running : wants to run, may not actually be running
558 S - sleep : process is waiting to be woken up (handles signals)
559 D - disk sleep (uninterruptible sleep) : process must be woken up
560 (ignores signals)
561 T - stopped : process suspended
562 t - traced : process is being traced (with something like gdb)
563 Z - zombie : process waiting to be cleaned up
564 X - unknown
565
566
567ftrace_enabled 457ftrace_enabled
568-------------- 458--------------
569 459