Messages in this thread | | | Subject | Re: tracing: confusing output of function_graph when notrace function calls traceable function | From | Steven Rostedt <> | Date | Wed, 06 Jan 2010 10:16:37 -0500 |
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On Wed, 2010-01-06 at 14:08 +0100, Jiri Olsa wrote: > On Wed, Jan 06, 2010 at 06:44:02PM +0800, Lai Jiangshan wrote: > > 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()
?? And that is exactly what the above shows.
> > > > 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? > I dont think so.. > > AFAIK the depth computation is based on the traced functions, and there's > no other 'depth related' input apart from them.
Right.
Honestly, if you think about it, the "father_fun()" does call those grandchild_fun() functions. Just indirectly. I don't find anything wrong with this.
You get the same issue if gcc decides to inline a function, since those inlined functions don't get traced either.
-- Steve
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