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| author | Divya Indi <divya.indi@oracle.com> | 2019-11-20 11:08:39 -0800 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-11-22 19:41:08 -0500 |
| commit | 89ed42495ef4a020435f2b999093bb5731eeb8b9 (patch) | |
| tree | 68ef747d890a706369a7b990e398bdc73502dfd7 /samples/Kconfig | |
| parent | 28879787147358e8ffcae397f11748de3dd26577 (diff) | |
| download | linux-89ed42495ef4a020435f2b999093bb5731eeb8b9.tar.bz2 | |
tracing: Sample module to demonstrate kernel access to Ftrace instances.
This is a sample module to demonstrate the use of the newly introduced and
exported APIs to access Ftrace instances from within the kernel.
Newly introduced APIs used here -
1. Create/Lookup a trace array with the given name.
struct trace_array *trace_array_get_by_name(const char *name)
2. Destroy/Remove a trace array.
int trace_array_destroy(struct trace_array *tr)
4. Enable/Disable trace events:
int trace_array_set_clr_event(struct trace_array *tr, const char *system,
const char *event, bool enable);
Exported APIs -
1. trace_printk equivalent for instances.
int trace_array_printk(struct trace_array *tr,
unsigned long ip, const char *fmt, ...);
2. Helper function.
void trace_printk_init_buffers(void);
3. To decrement the reference counter.
void trace_array_put(struct trace_array *tr)
Sample output(contents of /sys/kernel/tracing/instances/sample-instance)
NOTE: Tracing disabled after ~5 sec)
_-----=> irqs-off
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / delay
TASK-PID CPU# |||| TIMESTAMP FUNCTION
| | | |||| | |
sample-instance-1452 [002] .... 49.430948: simple_thread: trace_array_printk: count=0
sample-instance-1452 [002] .... 49.430951: sample_event: count value=0 at jiffies=4294716608
sample-instance-1452 [002] .... 50.454847: simple_thread: trace_array_printk: count=1
sample-instance-1452 [002] .... 50.454849: sample_event: count value=1 at jiffies=4294717632
sample-instance-1452 [002] .... 51.478748: simple_thread: trace_array_printk: count=2
sample-instance-1452 [002] .... 51.478750: sample_event: count value=2 at jiffies=4294718656
sample-instance-1452 [002] .... 52.502652: simple_thread: trace_array_printk: count=3
sample-instance-1452 [002] .... 52.502655: sample_event: count value=3 at jiffies=4294719680
sample-instance-1452 [002] .... 53.526533: simple_thread: trace_array_printk: count=4
sample-instance-1452 [002] .... 53.526535: sample_event: count value=4 at jiffies=4294720704
sample-instance-1452 [002] .... 54.550438: simple_thread: trace_array_printk: count=5
sample-instance-1452 [002] .... 55.574336: simple_thread: trace_array_printk: count=6
Link: http://lkml.kernel.org/r/1574276919-11119-3-git-send-email-divya.indi@oracle.com
Reviewed-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Divya Indi <divya.indi@oracle.com>
[ Moved to samples/ftrace ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'samples/Kconfig')
| -rw-r--r-- | samples/Kconfig | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/samples/Kconfig b/samples/Kconfig index 65b5967dac0c..ad64b223f3d0 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -27,6 +27,13 @@ config SAMPLE_FTRACE_DIRECT This builds an ftrace direct function example that hooks to wake_up_process and prints the parameters. +config SAMPLE_TRACE_ARRAY + tristate "Build sample module for kernel access to Ftrace instancess" + depends on EVENT_TRACING && m + help + This builds a module that demonstrates the use of various APIs to + access Ftrace instances from within the kernel. + config SAMPLE_KOBJECT tristate "Build kobject examples" help |