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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>
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Steven Rostedt
Steven Rostedt
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87d80de280
@ -202,10 +202,6 @@ Here is the list of current tracers that may be configured.
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to draw a graph of function calls similar to C code
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source.
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"sched_switch"
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Traces the context switches and wakeups between tasks.
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"irqsoff"
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Traces the areas that disable interrupts and saves
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@ -273,39 +269,6 @@ format, the function name that was traced "path_put" and the
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parent function that called this function "path_walk". The
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timestamp is the time at which the function was entered.
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The sched_switch tracer also includes tracing of task wakeups
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and context switches.
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ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 2916:115:S
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ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 10:115:S
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ksoftirqd/1-7 [01] 1453.070013: 7:115:R ==> 10:115:R
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events/1-10 [01] 1453.070013: 10:115:S ==> 2916:115:R
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kondemand/1-2916 [01] 1453.070013: 2916:115:S ==> 7:115:R
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ksoftirqd/1-7 [01] 1453.070013: 7:115:S ==> 0:140:R
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Wake ups are represented by a "+" and the context switches are
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shown as "==>". The format is:
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Context switches:
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Previous task Next Task
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<pid>:<prio>:<state> ==> <pid>:<prio>:<state>
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Wake ups:
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Current task Task waking up
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<pid>:<prio>:<state> + <pid>:<prio>:<state>
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The prio is the internal kernel priority, which is the inverse
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of the priority that is usually displayed by user-space tools.
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Zero represents the highest priority (99). Prio 100 starts the
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"nice" priorities with 100 being equal to nice -20 and 139 being
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nice 19. The prio "140" is reserved for the idle task which is
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the lowest priority thread (pid 0).
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Latency trace format
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--------------------
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@ -491,79 +454,6 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
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latencies, as described in "Latency
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trace format".
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sched_switch
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------------
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This tracer simply records schedule switches. Here is an example
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of how to use it.
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# echo sched_switch > current_tracer
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# echo 1 > tracing_enabled
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# sleep 1
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# echo 0 > tracing_enabled
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# cat trace
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# tracer: sched_switch
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#
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# TASK-PID CPU# TIMESTAMP FUNCTION
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# | | | | |
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bash-3997 [01] 240.132281: 3997:120:R + 4055:120:R
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bash-3997 [01] 240.132284: 3997:120:R ==> 4055:120:R
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sleep-4055 [01] 240.132371: 4055:120:S ==> 3997:120:R
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bash-3997 [01] 240.132454: 3997:120:R + 4055:120:S
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bash-3997 [01] 240.132457: 3997:120:R ==> 4055:120:R
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sleep-4055 [01] 240.132460: 4055:120:D ==> 3997:120:R
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bash-3997 [01] 240.132463: 3997:120:R + 4055:120:D
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bash-3997 [01] 240.132465: 3997:120:R ==> 4055:120:R
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<idle>-0 [00] 240.132589: 0:140:R + 4:115:S
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<idle>-0 [00] 240.132591: 0:140:R ==> 4:115:R
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ksoftirqd/0-4 [00] 240.132595: 4:115:S ==> 0:140:R
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<idle>-0 [00] 240.132598: 0:140:R + 4:115:S
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<idle>-0 [00] 240.132599: 0:140:R ==> 4:115:R
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ksoftirqd/0-4 [00] 240.132603: 4:115:S ==> 0:140:R
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sleep-4055 [01] 240.133058: 4055:120:S ==> 3997:120:R
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[...]
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As we have discussed previously about this format, the header
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shows the name of the trace and points to the options. The
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"FUNCTION" is a misnomer since here it represents the wake ups
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and context switches.
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The sched_switch file only lists the wake ups (represented with
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'+') and context switches ('==>') with the previous task or
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current task first followed by the next task or task waking up.
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The format for both of these is PID:KERNEL-PRIO:TASK-STATE.
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Remember that the KERNEL-PRIO is the inverse of the actual
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priority with zero (0) being the highest priority and the nice
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values starting at 100 (nice -20). Below is a quick chart to map
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the kernel priority to user land priorities.
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Kernel Space User Space
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===============================================================
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0(high) to 98(low) user RT priority 99(high) to 1(low)
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with SCHED_RR or SCHED_FIFO
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---------------------------------------------------------------
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99 sched_priority is not used in scheduling
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decisions(it must be specified as 0)
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---------------------------------------------------------------
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100(high) to 139(low) user nice -20(high) to 19(low)
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---------------------------------------------------------------
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140 idle task priority
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---------------------------------------------------------------
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The task states are:
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R - running : wants to run, may not actually be running
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S - sleep : process is waiting to be woken up (handles signals)
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D - disk sleep (uninterruptible sleep) : process must be woken up
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(ignores signals)
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T - stopped : process suspended
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t - traced : process is being traced (with something like gdb)
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Z - zombie : process waiting to be cleaned up
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X - unknown
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ftrace_enabled
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--------------
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@ -247,51 +247,3 @@ void tracing_sched_switch_assign_trace(struct trace_array *tr)
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ctx_trace = tr;
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}
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static void stop_sched_trace(struct trace_array *tr)
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{
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tracing_stop_sched_switch_record();
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}
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static int sched_switch_trace_init(struct trace_array *tr)
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{
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ctx_trace = tr;
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tracing_reset_online_cpus(tr);
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tracing_start_sched_switch_record();
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return 0;
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}
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static void sched_switch_trace_reset(struct trace_array *tr)
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{
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if (sched_ref)
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stop_sched_trace(tr);
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}
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static void sched_switch_trace_start(struct trace_array *tr)
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{
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sched_stopped = 0;
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}
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static void sched_switch_trace_stop(struct trace_array *tr)
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{
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sched_stopped = 1;
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}
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static struct tracer sched_switch_trace __read_mostly =
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{
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.name = "sched_switch",
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.init = sched_switch_trace_init,
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.reset = sched_switch_trace_reset,
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.start = sched_switch_trace_start,
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.stop = sched_switch_trace_stop,
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.wait_pipe = poll_wait_pipe,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_sched_switch,
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#endif
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};
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__init static int init_sched_switch_trace(void)
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{
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return register_tracer(&sched_switch_trace);
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}
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device_initcall(init_sched_switch_trace);
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