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SubjectRe: [PATCH v2 1/2] ftrace: Add task_comm support for trace_event
Hi,


On Fri, May 22, 2009 at 06:05:37PM +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>


Thanks!
This is fine but I think it can be factorized.

You could call start_cmdline_record() from

ftrace_raw_reg_event_##call()

and the stop in

ftrace_raw_unreg_event_##call()

No?

Frederic.


> ---
> kernel/trace/Kconfig | 1 +
> kernel/trace/trace_events.c | 6 ++++++
> 2 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index f61be30..dffbb77 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -187,6 +187,7 @@ config CONTEXT_SWITCH_TRACER
> config ENABLE_EVENT_TRACING
> bool "Trace various events in the kernel"
> select TRACING
> + select CONTEXT_SWITCH_TRACER
> help
> This tracer hooks to various trace points in the kernel
> allowing the user to pick and choose which trace point they
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 0eec0c5..df35e5e 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






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