From: Liam R. Howlett Date: Wed, 17 May 2017 15:47:00 +0000 (-0400) Subject: sparc/ftrace: Fix ftrace graph time measurement X-Git-Tag: v5.15~11271^2 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=48078d2dac0a26f84f5f3ec704f24f7c832cce14;p=mirror_ubuntu-kernels.git sparc/ftrace: Fix ftrace graph time measurement 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 Signed-off-by: David S. Miller --- 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(¤t->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; }