Using ftrace function-graph to examine the times consumed by
functions, the time shows up on the line where the call is made
if no other traceable functions were called by that function:
11) 0.672 us | cmd_alloc [hpsa]();
but the time shows up down by the } if the were other traceable
functions called by that function:
11) | cmd_alloc [hpsa]() {
11) 0.129 us | cmd_free [hpsa]();
11) 0.106 us | cmd_free [hpsa]();
11) 2.014 us | }
On its own, the } line doesn't indicate which function it is
closing, so grep cannot be used to search for all the times
for this function. You have to write a parser.
The function name does get printed on those lines when the
start of the function is off the trace.
This patch series adds a funcgraph-tail option to do that
in all cases.
echo 1 > /sys/kernel/debug/tracing/options/funcgraph-tail
or
echo funcgraph-tail > /sys/kernel/debug/tracing/trace_options
yields:
11) | hpsa_scsi_ioaccel_raid_map [hpsa]() {
11) | hpsa_scsi_ioaccel_queue_command [hpsa]() {
11) | hpsa_scsi_ioaccel2_queue_command [hpsa]() {
11) 0.067 us | fixup_ioaccel_cdb [hpsa]();
11) 0.053 us | set_encrypt_ioaccel2 [hpsa]();
11) 0.199 us | enqueue_cmd_and_start_io [hpsa]();
11) 1.952 us | } /* hpsa_scsi_ioaccel2_queue_command [hpsa] */
11) 2.501 us | } /* hpsa_scsi_ioaccel_queue_command [hpsa] */
11) 3.093 us | } /* hpsa_scsi_ioaccel_raid_map [hpsa] */
11) 4.667 us | } /* hpsa_scsi_queue_command [hpsa] */
echo 0 > /sys/kernel/debug/tracing/options/funcgraph-tail
or
echo nofuncgraph-tail > /sys/kernel/debug/tracing/trace_options
(which is the default setting) still yields:
11) | hpsa_scsi_ioaccel_raid_map [hpsa]() {
11) | hpsa_scsi_ioaccel_queue_command [hpsa]() {
11) | hpsa_scsi_ioaccel2_queue_command [hpsa]() {
11) 0.067 us | fixup_ioaccel_cdb [hpsa]();
11) 0.053 us | set_encrypt_ioaccel2 [hpsa]();
11) 0.199 us | enqueue_cmd_and_start_io [hpsa]();
11) 1.952 us | }
11) 2.501 us | }
11) 3.093 us | }
11) 4.667 us | }
---
Robert Elliott (2):
ftrace: Eliminate duplicate TRACE_GRAPH_PRINT_xx defines
ftrace: Add funcgraph_tail option to print function name after closing
braces
Documentation/trace/ftrace.txt | 26 ++++++++++++++++++++++++++
kernel/trace/trace.h | 2 ++
kernel/trace/trace_functions_graph.c | 18 ++++++------------
3 files changed, 34 insertions(+), 12 deletions(-)
--
Rob Elliott, HP Server Storage
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