perf trace: Add --max-summary option

The --max-summary option is to limit the number of output lines for
syscall summary stats.  The max applies to each entries like thread and
cgroups.  For total summary, it will just print up to the given number.

For example,

  $ sudo perf trace -as --max-summary 3 sleep 0.1

   ThreadPoolServi (1011651), 114 events, 14.8%

     syscall            calls  errors  total       min       avg       max       stddev
                                       (msec)    (msec)    (msec)    (msec)        (%)
     --------------- --------  ------ -------- --------- --------- ---------     ------
     epoll_wait            38      0    95.589     0.000     2.515    11.153     28.98%
     futex                  9      0     0.040     0.002     0.004     0.014     28.63%
     read                  10      0     0.037     0.003     0.004     0.005      4.67%

   sleep (1050529), 250 events, 32.4%

     syscall            calls  errors  total       min       avg       max       stddev
                                       (msec)    (msec)    (msec)    (msec)        (%)
     --------------- --------  ------ -------- --------- --------- ---------     ------
     clock_nanosleep        1      0   100.156   100.156   100.156   100.156      0.00%
     execve                 4      3     1.020     0.005     0.255     0.989     95.93%
     openat                36     17     0.416     0.003     0.012     0.029     10.58%

   ...

And this is for per-cgroup summary using BPF.

  $ sudo perf trace -as --max-summary 3 --summary-mode=cgroup --bpf-summary sleep 0.1

   cgroup /user.slice/user-657345.slice/user@657345.service/session.slice/org.gnome.Shell@x11.service, 12 events

     syscall            calls  errors  total       min       avg       max       stddev
                                       (msec)    (msec)    (msec)    (msec)        (%)
     --------------- --------  ------ -------- --------- --------- ---------     ------
     recvmsg                8      7     0.016     0.001     0.002     0.006     39.73%
     ppoll                  1      0     0.014     0.014     0.014     0.014      0.00%
     write                  2      0     0.010     0.002     0.005     0.008     61.02%

   cgroup /user.slice/user-657345.slice/session-4.scope, 73 events

     syscall            calls  errors  total       min       avg       max       stddev
                                       (msec)    (msec)    (msec)    (msec)        (%)
     --------------- --------  ------ -------- --------- --------- ---------     ------
     epoll_wait             8      0    13.461     0.010     1.683    12.235     89.66%
     ioctl                 20      0     0.204     0.001     0.010     0.113     54.01%
     writev                11      0     0.164     0.004     0.015     0.042     20.34%

Reviewed-by: Howard Chu <howardchu95@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index fe737b3ac6e6..5f54777d8ba0 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -196,6 +196,7 @@ struct trace {
 	unsigned int		max_stack;
 	unsigned int		min_stack;
 	enum trace_summary_mode	summary_mode;
+	int			max_summary;
 	int			raw_augmented_syscalls_args_size;
 	bool			raw_augmented_syscalls;
 	bool			fd_path_disabled;
@@ -4599,7 +4600,7 @@ out_disable:
 	if (!err) {
 		if (trace->summary) {
 			if (trace->summary_bpf)
-				trace_print_bpf_summary(trace->output);
+				trace_print_bpf_summary(trace->output, trace->max_summary);
 			else if (trace->summary_mode == SUMMARY__BY_TOTAL)
 				trace__fprintf_total_summary(trace, trace->output);
 			else
@@ -4822,6 +4823,7 @@ static size_t syscall__dump_stats(struct trace *trace, int e_machine, FILE *fp,
 				  struct hashmap *syscall_stats)
 {
 	size_t printed = 0;
+	int lines = 0;
 	struct syscall *sc;
 	struct syscall_entry *entries;
 
@@ -4866,7 +4868,11 @@ static size_t syscall__dump_stats(struct trace *trace, int e_machine, FILE *fp,
 						fprintf(fp, "\t\t\t\t%s: %d\n", perf_env__arch_strerrno(trace->host->env, e + 1), stats->errnos[e]);
 				}
 			}
+			lines++;
 		}
+
+		if (trace->max_summary && trace->max_summary <= lines)
+			break;
 	}
 
 	free(entries);
@@ -5443,6 +5449,8 @@ int cmd_trace(int argc, const char **argv)
 	OPT_BOOLEAN(0, "force-btf", &trace.force_btf, "Prefer btf_dump general pretty printer"
 		       "to customized ones"),
 	OPT_BOOLEAN(0, "bpf-summary", &trace.summary_bpf, "Summary syscall stats in BPF"),
+	OPT_INTEGER(0, "max-summary", &trace.max_summary,
+		     "Max number of entries in the summary."),
 	OPTS_EVSWITCH(&trace.evswitch),
 	OPT_END()
 	};