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Subject[tip: perf/core] perf tool: Provide an option to print perf_event_open args and return value
The following commit has been merged into the perf/core branch of tip:

Commit-ID: ccd26741f5e6bdf2c18ea38b32e6a347c5648a97
Gitweb: https://git.kernel.org/tip/ccd26741f5e6bdf2c18ea38b32e6a347c5648a97
Author: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
AuthorDate: Fri, 08 Nov 2019 15:11:28 +05:30
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitterDate: Tue, 12 Nov 2019 08:32:27 -03:00

perf tool: Provide an option to print perf_event_open args and return value

Perf record with verbose=2 already prints this information along with
whole lot of other traces which requires lot of scrolling. Introduce
an option to print only perf_event_open() arguments and return value.

Sample o/p:

$ perf --debug perf-event-open=1 record -- ls > /dev/null
------------------------------------------------------------
perf_event_attr:
size 112
{ sample_period, sample_freq } 4000
sample_type IP|TID|TIME|PERIOD
read_format ID
disabled 1
inherit 1
exclude_kernel 1
mmap 1
comm 1
freq 1
enable_on_exec 1
task 1
precise_ip 3
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
ksymbol 1
bpf_event 1
------------------------------------------------------------
sys_perf_event_open: pid 4308 cpu 0 group_fd -1 flags 0x8 = 4
sys_perf_event_open: pid 4308 cpu 1 group_fd -1 flags 0x8 = 5
sys_perf_event_open: pid 4308 cpu 2 group_fd -1 flags 0x8 = 6
sys_perf_event_open: pid 4308 cpu 3 group_fd -1 flags 0x8 = 8
sys_perf_event_open: pid 4308 cpu 4 group_fd -1 flags 0x8 = 9
sys_perf_event_open: pid 4308 cpu 5 group_fd -1 flags 0x8 = 10
sys_perf_event_open: pid 4308 cpu 6 group_fd -1 flags 0x8 = 11
sys_perf_event_open: pid 4308 cpu 7 group_fd -1 flags 0x8 = 12
------------------------------------------------------------
perf_event_attr:
type 1
size 112
config 0x9
watermark 1
sample_id_all 1
bpf_event 1
{ wakeup_events, wakeup_watermark } 1
------------------------------------------------------------
sys_perf_event_open: pid -1 cpu 0 group_fd -1 flags 0x8
sys_perf_event_open failed, error -13
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.002 MB perf.data (9 samples) ]

Committer notes:

Just like the 'verbose' variable this new 'debug_peo_args' needs to be
added to util/python.c, since we don't link the debug.o file in the
python binding, which ended up making 'perf test python' fail with:

# perf test -v python
18: 'import perf' in python :
--- start ---
test child forked, pid 19237
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /tmp/build/perf/python/perf.so: undefined symbol: debug_peo_args
test child finished with -1
---- end ----
'import perf' in python: FAILED!
#

After adding that new variable to util/python.c:

# perf test -v python
18: 'import perf' in python :
--- start ---
test child forked, pid 22364
test child finished with 0
---- end ----
'import perf' in python: Ok
#

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20191108094128.28769-1-ravi.bangoria@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf.txt | 2 ++-
tools/perf/util/debug.c | 2 ++-
tools/perf/util/debug.h | 9 ++++++++-
tools/perf/util/evsel.c | 36 +++++++++++++++---------------
tools/perf/util/python.c | 1 +-
5 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/tools/perf/Documentation/perf.txt b/tools/perf/Documentation/perf.txt
index 401f0ed..3f37ded 100644
--- a/tools/perf/Documentation/perf.txt
+++ b/tools/perf/Documentation/perf.txt
@@ -24,6 +24,8 @@ OPTIONS
data-convert - data convert command debug messages
stderr - write debug output (option -v) to stderr
in browser mode
+ perf-event-open - Print perf_event_open() arguments and
+ return value

--buildid-dir::
Setup buildid cache directory. It has higher priority than
diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
index e55114f..adb6567 100644
--- a/tools/perf/util/debug.c
+++ b/tools/perf/util/debug.c
@@ -24,6 +24,7 @@
#include <linux/ctype.h>

int verbose;
+int debug_peo_args;
bool dump_trace = false, quiet = false;
int debug_ordered_events;
static int redirect_to_stderr;
@@ -180,6 +181,7 @@ static struct debug_variable {
{ .name = "ordered-events", .ptr = &debug_ordered_events},
{ .name = "stderr", .ptr = &redirect_to_stderr},
{ .name = "data-convert", .ptr = &debug_data_convert },
+ { .name = "perf-event-open", .ptr = &debug_peo_args },
{ .name = NULL, }
};

diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
index d25ae1c..f1734ab 100644
--- a/tools/perf/util/debug.h
+++ b/tools/perf/util/debug.h
@@ -8,6 +8,7 @@
#include <linux/compiler.h>

extern int verbose;
+extern int debug_peo_args;
extern bool quiet, dump_trace;
extern int debug_ordered_events;
extern int debug_data_convert;
@@ -30,6 +31,14 @@ extern int debug_data_convert;
#define pr_debug3(fmt, ...) pr_debugN(3, pr_fmt(fmt), ##__VA_ARGS__)
#define pr_debug4(fmt, ...) pr_debugN(4, pr_fmt(fmt), ##__VA_ARGS__)

+/* Special macro to print perf_event_open arguments/return value. */
+#define pr_debug2_peo(fmt, ...) { \
+ if (debug_peo_args) \
+ pr_debugN(0, pr_fmt(fmt), ##__VA_ARGS__); \
+ else \
+ pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__); \
+}
+
#define pr_time_N(n, var, t, fmt, ...) \
eprintf_time(n, var, t, fmt, ##__VA_ARGS__)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index d445184..1bf60f3 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1524,7 +1524,7 @@ static int __open_attr__fprintf(FILE *fp, const char *name, const char *val,

static void display_attr(struct perf_event_attr *attr)
{
- if (verbose >= 2) {
+ if (verbose >= 2 || debug_peo_args) {
fprintf(stderr, "%.60s\n", graph_dotted_line);
fprintf(stderr, "perf_event_attr:\n");
perf_event_attr__fprintf(stderr, attr, __open_attr__fprintf, NULL);
@@ -1540,7 +1540,7 @@ static int perf_event_open(struct evsel *evsel,
int fd;

while (1) {
- pr_debug2("sys_perf_event_open: pid %d cpu %d group_fd %d flags %#lx",
+ pr_debug2_peo("sys_perf_event_open: pid %d cpu %d group_fd %d flags %#lx",
pid, cpu, group_fd, flags);

fd = sys_perf_event_open(&evsel->core.attr, pid, cpu, group_fd, flags);
@@ -1560,9 +1560,9 @@ static int perf_event_open(struct evsel *evsel,
break;
}

- pr_debug2("\nsys_perf_event_open failed, error %d\n", -ENOTSUP);
+ pr_debug2_peo("\nsys_perf_event_open failed, error %d\n", -ENOTSUP);
evsel->core.attr.precise_ip--;
- pr_debug2("decreasing precise_ip by one (%d)\n", evsel->core.attr.precise_ip);
+ pr_debug2_peo("decreasing precise_ip by one (%d)\n", evsel->core.attr.precise_ip);
display_attr(&evsel->core.attr);
}

@@ -1681,12 +1681,12 @@ retry_open:
continue;
}

- pr_debug2("\nsys_perf_event_open failed, error %d\n",
+ pr_debug2_peo("\nsys_perf_event_open failed, error %d\n",
err);
goto try_fallback;
}

- pr_debug2(" = %d\n", fd);
+ pr_debug2_peo(" = %d\n", fd);

if (evsel->bpf_fd >= 0) {
int evt_fd = fd;
@@ -1754,58 +1754,58 @@ try_fallback:
*/
if (!perf_missing_features.aux_output && evsel->core.attr.aux_output) {
perf_missing_features.aux_output = true;
- pr_debug2("Kernel has no attr.aux_output support, bailing out\n");
+ pr_debug2_peo("Kernel has no attr.aux_output support, bailing out\n");
goto out_close;
} else if (!perf_missing_features.bpf && evsel->core.attr.bpf_event) {
perf_missing_features.bpf = true;
- pr_debug2("switching off bpf_event\n");
+ pr_debug2_peo("switching off bpf_event\n");
goto fallback_missing_features;
} else if (!perf_missing_features.ksymbol && evsel->core.attr.ksymbol) {
perf_missing_features.ksymbol = true;
- pr_debug2("switching off ksymbol\n");
+ pr_debug2_peo("switching off ksymbol\n");
goto fallback_missing_features;
} else if (!perf_missing_features.write_backward && evsel->core.attr.write_backward) {
perf_missing_features.write_backward = true;
- pr_debug2("switching off write_backward\n");
+ pr_debug2_peo("switching off write_backward\n");
goto out_close;
} else if (!perf_missing_features.clockid_wrong && evsel->core.attr.use_clockid) {
perf_missing_features.clockid_wrong = true;
- pr_debug2("switching off clockid\n");
+ pr_debug2_peo("switching off clockid\n");
goto fallback_missing_features;
} else if (!perf_missing_features.clockid && evsel->core.attr.use_clockid) {
perf_missing_features.clockid = true;
- pr_debug2("switching off use_clockid\n");
+ pr_debug2_peo("switching off use_clockid\n");
goto fallback_missing_features;
} else if (!perf_missing_features.cloexec && (flags & PERF_FLAG_FD_CLOEXEC)) {
perf_missing_features.cloexec = true;
- pr_debug2("switching off cloexec flag\n");
+ pr_debug2_peo("switching off cloexec flag\n");
goto fallback_missing_features;
} else if (!perf_missing_features.mmap2 && evsel->core.attr.mmap2) {
perf_missing_features.mmap2 = true;
- pr_debug2("switching off mmap2\n");
+ pr_debug2_peo("switching off mmap2\n");
goto fallback_missing_features;
} else if (!perf_missing_features.exclude_guest &&
(evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host)) {
perf_missing_features.exclude_guest = true;
- pr_debug2("switching off exclude_guest, exclude_host\n");
+ pr_debug2_peo("switching off exclude_guest, exclude_host\n");
goto fallback_missing_features;
} else if (!perf_missing_features.sample_id_all) {
perf_missing_features.sample_id_all = true;
- pr_debug2("switching off sample_id_all\n");
+ pr_debug2_peo("switching off sample_id_all\n");
goto retry_sample_id;
} else if (!perf_missing_features.lbr_flags &&
(evsel->core.attr.branch_sample_type &
(PERF_SAMPLE_BRANCH_NO_CYCLES |
PERF_SAMPLE_BRANCH_NO_FLAGS))) {
perf_missing_features.lbr_flags = true;
- pr_debug2("switching off branch sample type no (cycles/flags)\n");
+ pr_debug2_peo("switching off branch sample type no (cycles/flags)\n");
goto fallback_missing_features;
} else if (!perf_missing_features.group_read &&
evsel->core.attr.inherit &&
(evsel->core.attr.read_format & PERF_FORMAT_GROUP) &&
perf_evsel__is_group_leader(evsel)) {
perf_missing_features.group_read = true;
- pr_debug2("switching off group read\n");
+ pr_debug2_peo("switching off group read\n");
goto fallback_missing_features;
}
out_close:
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 2511860..83212c6 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -65,6 +65,7 @@ struct perf_env perf_env;
* implementing 'verbose' and 'eprintf'.
*/
int verbose;
+int debug_peo_args;

int eprintf(int level, int var, const char *fmt, ...);

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