[PATCH 15/57] perf trace: Introduce --errno-summary

Arnaldo Carvalho de Melo
2019-10-21T13:43:00Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

To be used with -S or -s, using just this new option implies -s,
examples:

# perf trace --errno-summary sleep 1

Summary of events:

sleep (10793), 80 events, 93.0%

syscall calls errors total min avg max stddev
(msec) (msec) (msec) (msec) (%)
--------------- -------- ------ -------- --------- --------- --------- ------
nanosleep 1 0 1000.427 1000.427 1000.427 1000.427 0.00%
mmap 8 0 0.026 0.002 0.003 0.005 9.18%
close 5 0 0.018 0.001 0.004 0.009 48.97%
mprotect 4 0 0.017 0.003 0.004 0.006 16.49%
openat 3 0 0.012 0.003 0.004 0.005 9.41%
munmap 1 0 0.010 0.010 0.010 0.010 0.00%
brk 4 0 0.005 0.001 0.001 0.002 22.77%
read 4 0 0.005 0.001 0.001 0.002 22.33%
access 1 1 0.004 0.004 0.004 0.004 0.00%
ENOENT: 1
fstat 3 0 0.004 0.001 0.001 0.002 17.18%
lseek 3 0 0.003 0.001 0.001 0.001 11.62%
arch_prctl 2 1 0.002 0.001 0.001 0.001 3.32%
EINVAL: 1
execve 1 0 0.000 0.000 0.000 0.000 0.00%

#

Works as well together with --failure and -S, i.e. collect the stats and
show just the syscalls that failed:

# perf trace --failure -S --errno-summary sleep 1
0.032 arch_prctl(option: 0x3001, arg2: 0x7fffdb11b580) = -1 EINVAL (Invalid argument)
0.045 access(filename: "/etc/ld.so.preload", mode: R) = -1 ENOENT (No such file or directory)

Summary of events:

sleep (10806), 80 events, 93.0%

syscall calls errors total min avg max stddev
(msec) (msec) (msec) (msec) (%)
--------------- -------- ------ -------- --------- --------- --------- ------
nanosleep 1 0 1000.094 1000.094 1000.094 1000.094 0.00%
mmap 8 0 0.026 0.002 0.003 0.005 9.06%
close 5 0 0.018 0.001 0.004 0.010 49.58%
mprotect 4 0 0.017 0.003 0.004 0.006 17.56%
openat 3 0 0.014 0.004 0.005 0.006 12.29%
munmap 1 0 0.010 0.010 0.010 0.010 0.00%
brk 4 0 0.005 0.001 0.001 0.002 22.75%
read 4 0 0.005 0.001 0.001 0.002 17.19%
access 1 1 0.005 0.005 0.005 0.005 0.00%
ENOENT: 1
fstat 3 0 0.004 0.001 0.001 0.002 21.66%
lseek 3 0 0.003 0.001 0.001 0.001 11.71%
arch_prctl 2 1 0.002 0.001 0.001 0.001 2.66%
EINVAL: 1
execve 1 0 0.000 0.000 0.000 0.000 0.00%

#

Suggested-by: Andi Kleen <ak@linux.intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-l0mjwczkpouov7lss5zn8d9h@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-trace.txt | 4 ++
tools/perf/builtin-trace.c | 51 +++++++++++++++++++++++--
2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt
index 3bb89c2e9020..abc9b5d83312 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -146,6 +146,10 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs.
Show all syscalls followed by a summary by thread with min, max, and
average times (in msec) and relative stddev.

+--errno-summary::
+ To be used with -s or -S, to show stats for the errnos experienced by
+ syscalls, using only this option will trigger --summary.
+
--tool_stats::
Show tool stats such as number of times fd->pathname was discovered thru
hooking the open syscall return + vfs_getname or via reading /proc/pid/fd, etc.
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 56f2d72104a5..467e18e6f8ec 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -175,6 +175,7 @@ struct trace {
bool multiple_threads;
bool summary;
bool summary_only;
+ bool errno_summary;
bool failure_only;
bool show_comm;
bool print_sample;
@@ -1961,10 +1962,12 @@ static struct syscall *trace__syscall_info(struct trace *trace,
struct syscall_stats {
struct stats stats;
u64 nr_failures;
+ int max_errno;
+ u32 *errnos;
};

-static void thread__update_stats(struct thread_trace *ttrace,
- int id, struct perf_sample *sample, long err)
+static void thread__update_stats(struct thread *thread, struct thread_trace *ttrace,
+ int id, struct perf_sample *sample, long err, bool errno_summary)
{
struct int_node *inode;
struct syscall_stats *stats;
@@ -1981,6 +1984,8 @@ static void thread__update_stats(struct thread_trace *ttrace,
return;

stats->nr_failures = 0;
+ stats->max_errno = 0;
+ stats->errnos = NULL;
init_stats(&stats->stats);
inode->priv = stats;
}
@@ -1990,8 +1995,30 @@ static void thread__update_stats(struct thread_trace *ttrace,

update_stats(&stats->stats, duration);

- if (err < 0)
+ if (err < 0) {
++stats->nr_failures;
+
+ if (!errno_summary)
+ return;
+
+ err = -err;
+ if (err > stats->max_errno) {
+ u32 *new_errnos = realloc(stats->errnos, err * sizeof(u32));
+
+ if (new_errnos) {
+ memset(new_errnos + stats->max_errno, 0, (err - stats->max_errno) * sizeof(u32));
+ } else {
+ pr_debug("Not enough memory for errno stats for thread \"%s\"(%d/%d), results will be incomplete\n",
+ thread__comm_str(thread), thread->pid_, thread->tid);
+ return;
+ }
+
+ stats->errnos = new_errnos;
+ stats->max_errno = err;
+ }
+
+ ++stats->errnos[err - 1];
+ }
}

static int trace__printf_interrupted_entry(struct trace *trace)
@@ -2239,7 +2266,7 @@ static int trace__sys_exit(struct trace *trace, struct evsel *evsel,
ret = perf_evsel__sc_tp_uint(evsel, ret, sample);

if (trace->summary)
- thread__update_stats(ttrace, id, sample, ret);
+ thread__update_stats(thread, ttrace, id, sample, ret, trace->errno_summary);

if (!trace->fd_path_disabled && sc->is_open && ret >= 0 && ttrace->filename.pending_open) {
trace__set_fd_pathname(thread, ret, ttrace->filename.name);
@@ -4073,6 +4100,16 @@ static size_t thread__dump_stats(struct thread_trace *ttrace,
printed += fprintf(fp, " %8" PRIu64 " %6" PRIu64 " %9.3f %9.3f %9.3f",
n, stats->nr_failures, syscall_stats_entry->msecs, min, avg);
printed += fprintf(fp, " %9.3f %9.2f%%\n", max, pct);
+
+ if (trace->errno_summary && stats->nr_failures) {
+ const char *arch_name = perf_env__arch(trace->host->env);
+ int e;
+
+ for (e = 0; e < stats->max_errno; ++e) {
+ if (stats->errnos[e] != 0)
+ fprintf(fp, "\t\t\t\t%s: %d\n", arch_syscalls__strerrno(arch_name, e + 1), stats->errnos[e]);
+ }
+ }
}
}

@@ -4511,6 +4548,8 @@ int cmd_trace(int argc, const char **argv)
"Show only syscall summary with statistics"),
OPT_BOOLEAN('S', "with-summary", &trace.summary,
"Show all syscalls and summary with statistics"),
+ OPT_BOOLEAN(0, "errno-summary", &trace.errno_summary,
+ "Show errno stats per syscall, use with -s or -S"),
OPT_CALLBACK_DEFAULT('F', "pf", &trace.trace_pgfaults, "all|maj|min",
"Trace pagefaults", parse_pagefaults, "maj"),
OPT_BOOLEAN(0, "syscalls", &trace.trace_syscalls, "Trace syscalls"),
@@ -4816,6 +4855,10 @@ int cmd_trace(int argc, const char **argv)
if ((argc >= 1) && (strcmp(argv[0], "record") == 0))
return trace__record(&trace, argc-1, &argv[1]);

+ /* Using just --errno-summary will trigger --summary */
+ if (trace.errno_summary && !trace.summary && !trace.summary_only)
+ trace.summary_only = true;
+
/* summary_only implies summary option, but don't overwrite summary if set */
if (trace.summary_only)
trace.summary = trace.summary_only;
--
2.21.0