Messages in this thread | | | Subject | Re: [PATCH 09/10] tracing: Remove obsolete sched_switch tracer | From | Steven Rostedt <> | Date | Mon, 14 Feb 2011 14:42:00 -0500 |
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On Tue, 2011-02-08 at 17:16 -0500, Steven Rostedt wrote: > plain text document attachment > (0009-tracing-Remove-obsolete-sched_switch-tracer.patch) > From: Steven Rostedt <srostedt@redhat.com> > > 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.
Hmm, is this the right thing to do, or should we do the "WARN_ONCE()" when it is used, and give it a year to remove it?
-- Steve
> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org> > --- > Documentation/trace/ftrace.txt | 110 ------------------------------------- > kernel/trace/trace_sched_switch.c | 48 ---------------- > 2 files changed, 0 insertions(+), 158 deletions(-) > > diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt > index 557c1ed..65eddb7 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. > 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 > -------------- > > diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c > index 8f758d0..7e62c0a 100644 > --- a/kernel/trace/trace_sched_switch.c > +++ b/kernel/trace/trace_sched_switch.c > @@ -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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