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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/Makefile | |
| parent | 28879787147358e8ffcae397f11748de3dd26577 (diff) | |
| download | linux-89ed42495ef4a020435f2b999093bb5731eeb8b9.tar.gz linux-89ed42495ef4a020435f2b999093bb5731eeb8b9.tar.bz2 linux-89ed42495ef4a020435f2b999093bb5731eeb8b9.zip | |
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/Makefile')
| -rw-r--r-- | samples/Makefile | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/samples/Makefile b/samples/Makefile index cd496d633370..297f8934773f 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -18,6 +18,7 @@ subdir-$(CONFIG_SAMPLE_SECCOMP) += seccomp obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace_events/ obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace_printk/ obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace/ +obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += ftrace/ obj-$(CONFIG_VIDEO_PCI_SKELETON) += v4l/ obj-y += vfio-mdev/ subdir-$(CONFIG_SAMPLE_VFS) += vfs |