On Fri, Aug 14, 2020 at 09:24:40AM -0300, Arnaldo Carvalho de Melo wrote: > Em Sat, Aug 08, 2020 at 10:31:31AM +0800, Changbin Du escreveu: > > This adds support to display call trace for function tracer. To do this, > > just specify a '--func-opts call-graph' option. > > Applied, thanks for providing the usage example and the output of the > tool, please consider making this more compact and similar to the other > perf tools as: > > # perf ftrace -g -T vfs_read > > # perf report -h -g > > Usage: perf report [<options>] > > -g, --call-graph > <print_type,threshold[,print_limit],order,sort_key[,branch],value> > Display call graph (stack chain/backtrace): > > print_type: call graph printing style > (graph|flat|fractal|folded|none) > threshold: minimum call graph > inclusion threshold (<percent>) > print_limit: maximum number of call > graph entry (<number>) > order: call graph order > (caller|callee) > sort_key: call graph sort key > (function|address) > branch: include last branch info to > call graph (branch) > value: call graph value > (percent|period|count) > > Default: graph,0.5,caller,function,percent > > # > > Is there a way to ask for a limit in the number of levels? That is > similar to /proc/sys/kernel/perf_event_max_stack (system wide) and > perf_event_attr.sample_max_stack (per event)? > No, there is no such limit for function tracer yet (kernel doesn't support it). It just backtraces from current to top.
For graph tracer, the option is --graph-opts depth=<n>. > One can ask for that per event: > > # perf trace -e sched:*_wakeup/max-stack=2/ -e sched:*switch/max-stack=5/ > --max-events=4 > 0.000 migration/0/12 sched:sched_switch(prev_comm: "migration/0", > prev_pid: 12 (migration/0), prev_prio: 0, prev_state: 1, next_comm: > "swapper/0", next_pid: 0, next_prio: 120) > __schedule ([kernel.kallsyms]) > __schedule ([kernel.kallsyms]) > schedule ([kernel.kallsyms]) > smpboot_thread_fn ([kernel.kallsyms]) > kthread ([kernel.kallsyms]) > 2.381 :0/0 sched:sched_wakeup(comm: "PacerThread", pid: 111637 > (PacerThread), prio: 120, success: 1, target_cpu: 0) > ttwu_do_wakeup ([kernel.kallsyms]) > ttwu_do_wakeup ([kernel.kallsyms]) > 2.387 :0/0 sched:sched_switch(prev_comm: "swapper/0", prev_pid: 0, > prev_prio: 120, prev_state: 0, next_comm: "PacerThread", next_pid: 111637 > (PacerThread), next_prio: 120) > __schedule ([kernel.kallsyms]) > __schedule ([kernel.kallsyms]) > schedule_idle ([kernel.kallsyms]) > do_idle ([kernel.kallsyms]) > cpu_startup_entry ([kernel.kallsyms]) > 2.410 PacerThread/111637 sched:sched_switch(prev_comm: "PacerThread", > prev_pid: 111637 (PacerThread), prev_prio: 120, prev_state: 1, next_comm: > "swapper/0", next_pid: 0, next_prio: 120) > __schedule ([kernel.kallsyms]) > __schedule ([kernel.kallsyms]) > schedule ([kernel.kallsyms]) > futex_wait_queue_me ([kernel.kallsyms]) > futex_wait ([kernel.kallsyms]) > # > > - Arnaldo > > > $ sudo perf ftrace -T vfs_read --func-opts call-graph > > iio-sensor-prox-855 [003] 6168.369657: vfs_read <-ksys_read > > iio-sensor-prox-855 [003] 6168.369677: <stack trace> > > => vfs_read > > => ksys_read > > => __x64_sys_read > > => do_syscall_64 > > => entry_SYSCALL_64_after_hwframe > > ... > > > > Signed-off-by: Changbin Du <changbin...@gmail.com> > > > > --- > > v3: switch to uniform option --func-opts. > > v2: option name '-s' -> '--func-call-graph' > > --- > > tools/perf/Documentation/perf-ftrace.txt | 4 +++ > > tools/perf/builtin-ftrace.c | 42 ++++++++++++++++++++++++ > > 2 files changed, 46 insertions(+) > > > > diff --git a/tools/perf/Documentation/perf-ftrace.txt > > b/tools/perf/Documentation/perf-ftrace.txt > > index c46d0a09b38c..8f08ad0992c2 100644 > > --- a/tools/perf/Documentation/perf-ftrace.txt > > +++ b/tools/perf/Documentation/perf-ftrace.txt > > @@ -76,6 +76,10 @@ OPTIONS > > specify multiple functions (or glob patterns). It will be > > passed to 'set_ftrace_notrace' in tracefs. > > > > +--func-opts:: > > + List of options allowed to set: > > + call-graph - Display kernel stack trace for function tracer. > > + > > -G:: > > --graph-funcs=:: > > Select function_graph tracer and set graph filter on the given > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > > index 07b81d0c1658..469b89748c42 100644 > > --- a/tools/perf/builtin-ftrace.c > > +++ b/tools/perf/builtin-ftrace.c > > @@ -27,6 +27,7 @@ > > #include "util/cap.h" > > #include "util/config.h" > > #include "util/units.h" > > +#include "util/parse-sublevel-options.h" > > > > #define DEFAULT_TRACER "function_graph" > > > > @@ -42,6 +43,7 @@ struct perf_ftrace { > > int graph_depth; > > unsigned long percpu_buffer_size; > > bool inherit; > > + int func_stack_trace; > > }; > > > > struct filter_entry { > > @@ -202,6 +204,7 @@ static void reset_tracing_filters(void); > > static void reset_tracing_options(struct perf_ftrace *ftrace > > __maybe_unused) > > { > > write_tracing_option_file("function-fork", "0"); > > + write_tracing_option_file("func_stack_trace", "0"); > > } > > > > static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused) > > @@ -278,6 +281,17 @@ static int set_tracing_cpu(struct perf_ftrace *ftrace) > > return set_tracing_cpumask(cpumap); > > } > > > > +static int set_tracing_func_stack_trace(struct perf_ftrace *ftrace) > > +{ > > + if (!ftrace->func_stack_trace) > > + return 0; > > + > > + if (write_tracing_option_file("func_stack_trace", "1") < 0) > > + return -1; > > + > > + return 0; > > +} > > + > > static int reset_tracing_cpu(void) > > { > > struct perf_cpu_map *cpumap = perf_cpu_map__new(NULL); > > @@ -426,6 +440,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, > > int argc, const char **argv) > > goto out_reset; > > } > > > > + if (set_tracing_func_stack_trace(ftrace) < 0) { > > + pr_err("failed to set tracing option func_stack_trace\n"); > > + goto out_reset; > > + } > > + > > if (set_tracing_filters(ftrace) < 0) { > > pr_err("failed to set tracing filters\n"); > > goto out_reset; > > @@ -598,6 +617,26 @@ static int parse_buffer_size(const struct option *opt, > > return -1; > > } > > > > +static int parse_func_tracer_opts(const struct option *opt, > > + const char *str, int unset) > > +{ > > + int ret; > > + struct perf_ftrace *ftrace = (struct perf_ftrace *) opt->value; > > + struct sublevel_option func_tracer_opts[] = { > > + { .name = "call-graph", .value_ptr = &ftrace->func_stack_trace > > }, > > + { .name = NULL, } > > + }; > > + > > + if (unset) > > + return 0; > > + > > + ret = perf_parse_sublevel_options(str, func_tracer_opts); > > + if (ret) > > + return ret; > > + > > + return 0; > > +} > > + > > static void select_tracer(struct perf_ftrace *ftrace) > > { > > bool graph = !list_empty(&ftrace->graph_funcs) || > > @@ -645,6 +684,9 @@ int cmd_ftrace(int argc, const char **argv) > > parse_filter_func), > > OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func", > > "do not trace given functions", parse_filter_func), > > + OPT_CALLBACK(0, "func-opts", &ftrace, "options", > > + "function tracer options, available options: call-graph", > > + parse_func_tracer_opts), > > OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func", > > "trace given functions using function_graph tracer", > > parse_filter_func), > > -- > > 2.25.1 > > > > -- > > - Arnaldo -- Cheers, Changbin Du