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Commit 87d80de2 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
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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: default avatarSteven Rostedt <rostedt@goodmis.org>
parent f4d5c029
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Documentation/trace/ftrace.txt
View file @ 87d80de2
......@@ -202,10 +202,6 @@ Here is the list of current tracers that may be configured.
to draw a graph of function calls similar to C code
source.
"sched_switch"
Traces the context switches and wakeups between tasks.
"irqsoff"
Traces the areas that disable interrupts and saves
......@@ -273,39 +269,6 @@ format, the function name that was traced "path_put" and the
parent function that called this function "path_walk". The
timestamp is the time at which the function was entered.
The sched_switch tracer also includes tracing of task wakeups
and context switches.
ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 2916:115:S
ksoftirqd/1-7 [01] 1453.070013: 7:115:R + 10:115:S
ksoftirqd/1-7 [01] 1453.070013: 7:115:R ==> 10:115:R
events/1-10 [01] 1453.070013: 10:115:S ==> 2916:115:R
kondemand/1-2916 [01] 1453.070013: 2916:115:S ==> 7:115:R
ksoftirqd/1-7 [01] 1453.070013: 7:115:S ==> 0:140:R
Wake ups are represented by a "+" and the context switches are
shown as "==>". The format is:
Context switches:
Previous task Next Task
<pid>:<prio>:<state> ==> <pid>:<prio>:<state>
Wake ups:
Current task Task waking up
<pid>:<prio>:<state> + <pid>:<prio>:<state>
The prio is the internal kernel priority, which is the inverse
of the priority that is usually displayed by user-space tools.
Zero represents the highest priority (99). Prio 100 starts the
"nice" priorities with 100 being equal to nice -20 and 139 being
nice 19. The prio "140" is reserved for the idle task which is
the lowest priority thread (pid 0).
Latency trace format
--------------------
......@@ -491,79 +454,6 @@ x494] <- /root/a.out[+0x4a8] <- /lib/libc-2.7.so[+0x1e1a6]
latencies, as described in "Latency
trace format".
sched_switch
------------
This tracer simply records schedule switches. Here is an example
of how to use it.
# echo sched_switch > current_tracer
# echo 1 > tracing_enabled
# sleep 1
# echo 0 > tracing_enabled
# cat trace
# tracer: sched_switch
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
bash-3997 [01] 240.132281: 3997:120:R + 4055:120:R
bash-3997 [01] 240.132284: 3997:120:R ==> 4055:120:R
sleep-4055 [01] 240.132371: 4055:120:S ==> 3997:120:R
bash-3997 [01] 240.132454: 3997:120:R + 4055:120:S
bash-3997 [01] 240.132457: 3997:120:R ==> 4055:120:R
sleep-4055 [01] 240.132460: 4055:120:D ==> 3997:120:R
bash-3997 [01] 240.132463: 3997:120:R + 4055:120:D
bash-3997 [01] 240.132465: 3997:120:R ==> 4055:120:R
<idle>-0 [00] 240.132589: 0:140:R + 4:115:S
<idle>-0 [00] 240.132591: 0:140:R ==> 4:115:R
ksoftirqd/0-4 [00] 240.132595: 4:115:S ==> 0:140:R
<idle>-0 [00] 240.132598: 0:140:R + 4:115:S
<idle>-0 [00] 240.132599: 0:140:R ==> 4:115:R
ksoftirqd/0-4 [00] 240.132603: 4:115:S ==> 0:140:R
sleep-4055 [01] 240.133058: 4055:120:S ==> 3997:120:R
[...]
As we have discussed previously about this format, the header
shows the name of the trace and points to the options. The
"FUNCTION" is a misnomer since here it represents the wake ups
and context switches.
The sched_switch file only lists the wake ups (represented with
'+') and context switches ('==>') with the previous task or
current task first followed by the next task or task waking up.
The format for both of these is PID:KERNEL-PRIO:TASK-STATE.
Remember that the KERNEL-PRIO is the inverse of the actual
priority with zero (0) being the highest priority and the nice
values starting at 100 (nice -20). Below is a quick chart to map
the kernel priority to user land priorities.
Kernel Space User Space
===============================================================
0(high) to 98(low) user RT priority 99(high) to 1(low)
with SCHED_RR or SCHED_FIFO
---------------------------------------------------------------
99 sched_priority is not used in scheduling
decisions(it must be specified as 0)
---------------------------------------------------------------
100(high) to 139(low) user nice -20(high) to 19(low)
---------------------------------------------------------------
140 idle task priority
---------------------------------------------------------------
The task states are:
R - running : wants to run, may not actually be running
S - sleep : process is waiting to be woken up (handles signals)
D - disk sleep (uninterruptible sleep) : process must be woken up
(ignores signals)
T - stopped : process suspended
t - traced : process is being traced (with something like gdb)
Z - zombie : process waiting to be cleaned up
X - unknown
ftrace_enabled
--------------
......
kernel/trace/trace_sched_switch.c
View file @ 87d80de2
......@@ -247,51 +247,3 @@ void tracing_sched_switch_assign_trace(struct trace_array *tr)
ctx_trace = tr;
}
static void stop_sched_trace(struct trace_array *tr)
{
tracing_stop_sched_switch_record();
}
static int sched_switch_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
tracing_reset_online_cpus(tr);
tracing_start_sched_switch_record();
return 0;
}
static void sched_switch_trace_reset(struct trace_array *tr)
{
if (sched_ref)
stop_sched_trace(tr);
}
static void sched_switch_trace_start(struct trace_array *tr)
{
sched_stopped = 0;
}
static void sched_switch_trace_stop(struct trace_array *tr)
{
sched_stopped = 1;
}
static struct tracer sched_switch_trace __read_mostly =
{
.name = "sched_switch",
.init = sched_switch_trace_init,
.reset = sched_switch_trace_reset,
.start = sched_switch_trace_start,
.stop = sched_switch_trace_stop,
.wait_pipe = poll_wait_pipe,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_sched_switch,
#endif
};
__init static int init_sched_switch_trace(void)
{
return register_tracer(&sched_switch_trace);
}
device_initcall(init_sched_switch_trace);
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