From: Arnaldo Carvalho de Melo <[email protected]>
The kernel parts are not that useful:
# trace -m 512 -e nanosleep --call dwarf usleep 1
0.065 ( 0.065 ms): usleep/18732 nanosleep(rqtp: 0x7ffc4ee4e200) = 0
syscall_slow_exit_work
([kernel.kallsyms])
do_syscall_64 ([kernel.kallsyms])
return_from_SYSCALL_64
([kernel.kallsyms])
__nanosleep (/usr/lib64/libc-2.22.so)
usleep (/usr/lib64/libc-2.22.so)
main (/usr/bin/usleep)
__libc_start_main
(/usr/lib64/libc-2.22.so)
_start (/usr/bin/usleep)
#
So lets just use perf_event_attr.exclude_callchain_kernel to avoid
collecting it in the ring buffer:
# trace -m 512 -e nanosleep --call dwarf usleep 1
0.063 ( 0.063 ms): usleep/19212 nanosleep(rqtp: 0x7ffc3df10fb0) = 0
__nanosleep (/usr/lib64/libc-2.22.so)
usleep (/usr/lib64/libc-2.22.so)
main (/usr/bin/usleep)
__libc_start_main
(/usr/lib64/libc-2.22.so)
_start (/usr/bin/usleep)
#
Cc: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Milian Wolff <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Wang Nan <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/Documentation/perf-trace.txt | 3 +++
tools/perf/builtin-trace.c | 13 +++++++++++++
2 files changed, 16 insertions(+)
diff --git a/tools/perf/Documentation/perf-trace.txt
b/tools/perf/Documentation/perf-trace.txt
index ed485df16409..1bbcf305d233 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -123,6 +123,9 @@ the thread executes on the designated CPUs. Default is to
monitor all CPUs.
man pages for details. The ones that are most useful in 'perf trace'
are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph
dwarf'.
+--kernel-syscall-graph::
+ Show the kernel callchains on the syscall exit path.
+
--event::
Trace other events, see 'perf list' for a complete list.
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 63a3cc9b717c..cfa5ce8fdb7b 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -159,6 +159,7 @@ struct trace {
bool show_comm;
bool show_tool_stats;
bool trace_syscalls;
+ bool kernel_syscallchains;
bool force;
bool vfs_getname;
int trace_pgfaults;
@@ -2661,6 +2662,15 @@ static int trace__add_syscall_newtp(struct trace *trace)
perf_evlist__add(evlist, sys_enter);
perf_evlist__add(evlist, sys_exit);
+ if (trace->opts.callgraph_set && !trace->kernel_syscallchains) {
+ /*
+ * We're interested only in the user space callchain
+ * leading to the syscall, allow overriding that for
+ * debugging reasons using --kernel_syscall_callchains
+ */
+ sys_exit->attr.exclude_callchain_kernel = 1;
+ }
+
trace->syscalls.events.sys_enter = sys_enter;
trace->syscalls.events.sys_exit = sys_exit;
@@ -3221,6 +3231,7 @@ int cmd_trace(int argc, const char **argv, const char
*prefix __maybe_unused)
.output = stderr,
.show_comm = true,
.trace_syscalls = true,
+ .kernel_syscallchains = false,
};
const char *output_name = NULL;
const char *ev_qualifier_str = NULL;
@@ -3269,6 +3280,8 @@ int cmd_trace(int argc, const char **argv, const char
*prefix __maybe_unused)
OPT_CALLBACK(0, "call-graph", &trace.opts,
"record_mode[,record_size]", record_callchain_help,
&record_parse_callchain_opt),
+ OPT_BOOLEAN(0, "kernel-syscall-graph", &trace.kernel_syscallchains,
+ "Show the kernel callchains on the syscall exit path"),
OPT_UINTEGER(0, "proc-map-timeout", &trace.opts.proc_map_timeout,
"per thread proc mmap processing timeout in ms"),
OPT_END()
--
2.5.5
