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authorLiam R. Howlett <Liam.Howlett@Oracle.com>2017-05-17 11:47:00 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-07 12:07:46 +0200
commit1a658771d5e129c64b34ce22d3018665d631c173 (patch)
tree399442b40933f04b9129bf3964fdda5ed0c2b77d /arch/sparc
parent45ceb845ef34984357e6c2e0170570cc6f7179a3 (diff)
sparc/ftrace: Fix ftrace graph time measurement
[ Upstream commit 48078d2dac0a26f84f5f3ec704f24f7c832cce14 ] The ftrace function_graph time measurements of a given function is not accurate according to those recorded by ftrace using the function filters. This change pulls the x86_64 fix from 'commit 722b3c746953 ("ftrace/graph: Trace function entry before updating index")' into the sparc specific prepare_ftrace_return which stops ftrace from counting interrupted tasks in the time measurement. Example measurements for select_task_rq_fair running "hackbench 100 process 1000": | tracing/trace_stat/function0 | function_graph Before patch | 2.802 us | 4.255 us After patch | 2.749 us | 3.094 us Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/sparc')
-rw-r--r--arch/sparc/kernel/ftrace.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/arch/sparc/kernel/ftrace.c b/arch/sparc/kernel/ftrace.c
index 6bcff698069b..cec54dc4ab81 100644
--- a/arch/sparc/kernel/ftrace.c
+++ b/arch/sparc/kernel/ftrace.c
@@ -130,17 +130,16 @@ unsigned long prepare_ftrace_return(unsigned long parent,
if (unlikely(atomic_read(&current->tracing_graph_pause)))
return parent + 8UL;
- if (ftrace_push_return_trace(parent, self_addr, &trace.depth,
- frame_pointer, NULL) == -EBUSY)
- return parent + 8UL;
-
trace.func = self_addr;
+ trace.depth = current->curr_ret_stack + 1;
/* Only trace if the calling function expects to */
- if (!ftrace_graph_entry(&trace)) {
- current->curr_ret_stack--;
+ if (!ftrace_graph_entry(&trace))
+ return parent + 8UL;
+
+ if (ftrace_push_return_trace(parent, self_addr, &trace.depth,
+ frame_pointer, NULL) == -EBUSY)
return parent + 8UL;
- }
return return_hooker;
}