lkml.org 
[lkml]   [2011]   [Feb]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 09/10] tracing: Remove obsolete sched_switch tracer
    From
    Date
    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);
    > -




    \
     
     \ /
      Last update: 2011-02-14 20:45    [W:6.503 / U:0.320 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site