diff options
author | Steven Noonan <steven@uplinklabs.net> | 2008-09-19 10:06:43 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-10-14 08:37:43 (GMT) |
commit | fb1b6d8b5154c692172a424e45fbd0573295cb93 (patch) | |
tree | d9a7ad2c629a6133998402354e77cd721e4962b4 | |
parent | 5bf9a1ee350a10feb94107de32a203d81fbbe706 (diff) | |
download | linux-fsl-qoriq-fb1b6d8b5154c692172a424e45fbd0573295cb93.tar.xz |
ftrace: add nop tracer
A no-op tracer which can serve two purposes:
1. A template for development of a new tracer.
2. A convenient way to see ftrace_printk() calls without
an irrelevant trace making the output messy.
[ mingo@elte.hu: resolved conflicts ]
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r-- | kernel/trace/Kconfig | 10 | ||||
-rw-r--r-- | kernel/trace/Makefile | 1 | ||||
-rw-r--r-- | kernel/trace/trace.h | 4 | ||||
-rw-r--r-- | kernel/trace/trace_nop.c | 65 | ||||
-rw-r--r-- | kernel/trace/trace_selftest.c | 9 |
5 files changed, 89 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 16e5bb5..d7b2de7 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -101,6 +101,16 @@ 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 NOP_TRACER + bool "NOP Tracer" + depends on HAVE_FTRACE + depends on DEBUG_KERNEL + select TRACING + help + This tracer does nothing. The primary purpose for it is to + politely print the output of ftrace_printk() calls without + the overhead of an irrelevant trace taking place. + config CONTEXT_SWITCH_TRACER bool "Trace process context switches" depends on HAVE_FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 58ec61c..73ba13f 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -19,6 +19,7 @@ obj-$(CONFIG_FTRACE) += trace_functions.o obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o +obj-$(CONFIG_NOP_TRACER) += trace_nop.o obj-$(CONFIG_STACK_TRACER) += trace_stack.o obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 42f65d0..447d4b9 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -339,6 +339,10 @@ extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace, extern int trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr); #endif +#ifdef CONFIG_NOP_TRACER +extern int trace_selftest_startup_nop(struct tracer *trace, + struct trace_array *tr); +#endif #ifdef CONFIG_CONTEXT_SWITCH_TRACER extern int trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr); diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c new file mode 100644 index 0000000..dafaefb --- /dev/null +++ b/kernel/trace/trace_nop.c @@ -0,0 +1,65 @@ +/* + * nop tracer + * + * Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net> + * + */ + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/debugfs.h> +#include <linux/ftrace.h> + +#include "trace.h" + +static struct trace_array *ctx_trace; + +static void start_nop_trace(struct trace_array *tr) +{ + /* Nothing to do! */ +} + +static void stop_nop_trace(struct trace_array *tr) +{ + /* Nothing to do! */ +} + +static void nop_trace_init(struct trace_array *tr) +{ + ctx_trace = tr; + + if (tr->ctrl) + start_nop_trace(tr); +} + +static void nop_trace_reset(struct trace_array *tr) +{ + if (tr->ctrl) + stop_nop_trace(tr); +} + +static void nop_trace_ctrl_update(struct trace_array *tr) +{ + /* When starting a new trace, reset the buffers */ + if (tr->ctrl) + start_nop_trace(tr); + else + stop_nop_trace(tr); +} + +static struct tracer nop_trace __read_mostly = +{ + .name = "nop", + .init = nop_trace_init, + .reset = nop_trace_reset, + .ctrl_update = nop_trace_ctrl_update, +#ifdef CONFIG_FTRACE_SELFTEST + .selftest = trace_selftest_startup_nop, +#endif +}; + +__init static int init_nop_trace(void) +{ + return register_tracer(&nop_trace); +} +device_initcall(init_nop_trace); diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index 630715b..82db910 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -418,6 +418,15 @@ trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array * } #endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */ +#ifdef CONFIG_NOP_TRACER +int +trace_selftest_startup_nop(struct tracer *trace, struct trace_array *tr) +{ + /* What could possibly go wrong? */ + return 0; +} +#endif + #ifdef CONFIG_SCHED_TRACER static int trace_wakeup_test_thread(void *data) { |