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DateWed, 06 Jan 2010 18:44:02 +0800
FromLai Jiangshan <>
Subjecttracing: confusing output of function_graph when notrace function calls traceable function
cat <debugfs_dir>/tracing/trace
you can get these at the end of the outputs:

1) | nameidata_to_filp() {
1) | __dentry_open() {
1) | file_move() {
1) 0.834 us | _raw_spin_lock();
1) 0.926 us | _raw_spin_unlock();
1) 4.768 us | }
!!!! file_move() is really called by __dentry_open()
1) | kmem_cache_alloc_notrace() {
1) 5.879 us | memset();
1) + 12.390 us | }
1) 1.025 us | mutex_lock();
1) | kmem_cache_alloc_notrace() {
1) 0.929 us | memset();
1) 3.329 us | }
1) 1.195 us | memcpy();
1) 1.026 us | __mutex_init();
!!!! the above are actually called by __tracing_open() which called by __dentry_open()
(But at the first I was confused, I wondered why __dentry_open() calls them.)
1) | kmem_cache_alloc_notrace() {
1) 0.978 us | memset();
1) 2.745 us | }
1) | __alloc_percpu() {
1) | pcpu_alloc() {
1) 1.053 us | mutex_lock();
1) 1.282 us | _raw_spin_lock_irqsave();
1) | pcpu_size_to_slot() {
1) 0.819 us | __pcpu_size_to_slot();
1) 5.455 us | }
1) 1.135 us | pcpu_need_to_extend();
1) | pcpu_alloc_area() {
1) | pcpu_chunk_slot() {
1) | pcpu_size_to_slot() {
1) 0.813 us | __pcpu_size_to_slot();
1) 2.535 us | }
1) 8.349 us | }
1) 1.160 us | memmove();
1) | pcpu_chunk_relocate() {
1) | pcpu_chunk_slot() {
1) | pcpu_size_to_slot() {
1) 0.803 us | __pcpu_size_to_slot();
1) 2.478 us | }
1) 4.129 us | }
1) 8.583 us | }
1) + 29.665 us | }
1) 1.038 us | _raw_spin_unlock_irqrestore();
1) 1.178 us | pcpu_next_pop();
1) 1.087 us | pcpu_chunk_addr();
1) 0.975 us | memset();
1) 0.821 us | pcpu_chunk_addr();
1) 0.943 us | memset();
1) 0.896 us | mutex_unlock();
1) + 75.625 us | }
1) + 77.453 us | }
!!!! the above are actually called by graph_trace_open() which called by __tracing_open()
== real graph ==:

father_fun()
child_fun()
notrace_child_fun()
grandchild_fun1()
grandchild_fun2()

===function_graph shows===>

father_fun()
child_fun()
grandchild_fun1()
grandchild_fun2()

When the notrace function calls traceable function, function_graph will
get wrong depth of functions, and show wrong graph.

Is there any method to fix it?

Lai


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