lkml.org 
[lkml]   [2009]   [May]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 1/2] ftrace: Add task_comm support for trace_event
On Mon, May 25, 2009 at 06:11:59PM +0800, Zhaolei wrote:
> If we use trace_event alone(without function trace, .etc),
> it can't output enough task command information.
>
> Before patch:
> # echo 1 > debugfs/tracing/events/sched/sched_switch/enable
> # cat debugfs/tracing/trace
> # tracer: nop
> #
> # TASK-PID CPU# TIMESTAMP FUNCTION
> # | | | | |
> <...>-2289 [000] 526276.724790: sched_switch: task bash:2289 [120] ==> sshd:2287 [120]
> <...>-2287 [000] 526276.725231: sched_switch: task sshd:2287 [120] ==> bash:2289 [120]
> <...>-2289 [000] 526276.725452: sched_switch: task bash:2289 [120] ==> sshd:2287 [120]
> <...>-2287 [000] 526276.727181: sched_switch: task sshd:2287 [120] ==> swapper:0 [140]
> <idle>-0 [000] 526277.032734: sched_switch: task swapper:0 [140] ==> events/0:5 [115]
> <...>-5 [000] 526277.032782: sched_switch: task events/0:5 [115] ==> swapper:0 [140]
> ...
>
> After patch:
> # tracer: nop
> #
> # TASK-PID CPU# TIMESTAMP FUNCTION
> # | | | | |
> bash-2269 [000] 527347.989229: sched_switch: task bash:2269 [120] ==> sshd:2267 [120]
> sshd-2267 [000] 527347.990960: sched_switch: task sshd:2267 [120] ==> bash:2269 [120]
> bash-2269 [000] 527347.991143: sched_switch: task bash:2269 [120] ==> sshd:2267 [120]
> sshd-2267 [000] 527347.992959: sched_switch: task sshd:2267 [120] ==> swapper:0 [140]
> <idle>-0 [000] 527348.531989: sched_switch: task swapper:0 [140] ==> events/0:5 [115]
> events/0-5 [000] 527348.532115: sched_switch: task events/0:5 [115] ==> swapper:0 [140]
> ...
>
> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
> ---
> kernel/trace/Kconfig | 9 +++++++--
> kernel/trace/trace_events.c | 6 ++++++
> 2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index f61be30..a508b9d 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -49,6 +49,11 @@ config FTRACE_NMI_ENTER
> default y
>
> config EVENT_TRACING
> + select CONTEXT_SWITCH_TRACER
> + bool
> +
> +config CONTEXT_SWITCH_TRACER
> + select MARKERS
> bool
>
> config TRACING
> @@ -176,10 +181,10 @@ config SCHED_TRACER
> This tracer tracks the latency of the highest priority task
> to be scheduled in, starting from the point it has woken up.
>
> -config CONTEXT_SWITCH_TRACER
> +config ENABLE_CONTEXT_SWITCH_TRACER
> bool "Trace process context switches"
> select TRACING
> - select MARKERS
> + select CONTEXT_SWITCH_TRACER



I didn't like this part at a first glance.
But actually that makes sense.

I don't think it would be that worth to separate the cmdline record
from the sched switch tracer because they are both too tight in essence.

So this new ENABLE_CONTEXT_SWITCH_TRACER seems to me a good way
to solve this problem.

Thanks,
Frederic.



> help
> This tracer gets called from the context switch and records
> all switching of tasks.
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 9e91c4a..9b246eb 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -85,6 +85,7 @@ static void ftrace_clear_events(void)
>
> if (call->enabled) {
> call->enabled = 0;
> + tracing_stop_cmdline_record();
> call->unregfunc();
> }
> }
> @@ -99,12 +100,14 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
> case 0:
> if (call->enabled) {
> call->enabled = 0;
> + tracing_stop_cmdline_record();
> call->unregfunc();
> }
> break;
> case 1:
> if (!call->enabled) {
> call->enabled = 1;
> + tracing_start_cmdline_record();
> call->regfunc();
> }
> break;
> @@ -1058,6 +1061,7 @@ static void trace_module_remove_events(struct module *mod)
> found = true;
> if (call->enabled) {
> call->enabled = 0;
> + tracing_stop_cmdline_record();
> call->unregfunc();
> }
> if (call->event)
> @@ -1262,11 +1266,13 @@ static __init void event_trace_self_tests(void)
> }
>
> call->enabled = 1;
> + tracing_start_cmdline_record();
> call->regfunc();
>
> event_test_stuff();
>
> call->unregfunc();
> + tracing_stop_cmdline_record();
> call->enabled = 0;
>
> pr_cont("OK\n");
> --
> 1.5.5.3
>



\
 
 \ /
  Last update: 2009-05-26 02:47    [from the cache]
©2003-2011 Jasper Spaans