[v1] perf stat: Fix trailing comma when there is no metric unit

[PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

Posted by James Clark 1 month ago

We decided to hide NULL metric units rather than showing it as "(null)",
but on hybrid systems if the process doesn't hit a PMU you get an empty
string metric unit instead. To make it consistent also remove empty
strings.

Note that metric-threshold is already hidden in this case without this
change.

Where a process only runs on cpu_core and never hits cpu_atom:
Before:
 $ perf stat -j -- true
 ...
 {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
 {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
 ...

After:
 ...
 {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
 {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
 ...

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/perf/util/stat-display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index a5d72f4a515c..9b7fd985a42a 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
 	struct outstate *os = ctx;
 	FILE *out = os->fh;
 
-	if (unit) {
+	if (unit && strlen(unit)) {
 		json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
 		if (thresh != METRIC_THRESHOLD_UNKNOWN) {
 			json_out(os, "\"metric-threshold\" : \"%s\"",
-- 
2.34.1

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

Posted by Namhyung Kim 3 weeks, 5 days ago

Hello,

On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
> We decided to hide NULL metric units rather than showing it as "(null)",
> but on hybrid systems if the process doesn't hit a PMU you get an empty
> string metric unit instead. To make it consistent also remove empty
> strings.
> 
> Note that metric-threshold is already hidden in this case without this
> change.
> 
> Where a process only runs on cpu_core and never hits cpu_atom:
> Before:
>  $ perf stat -j -- true
>  ...
>  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
>  {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>  ...

I guess you're talking about "metric-unit", not plain "unit", right?
Then please update the subject line to reduce the config.

Ian, can you please review?

Thanks,
Namhyung

> 
> After:
>  ...
>  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
>  {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>  ...
> 
> Signed-off-by: James Clark <james.clark@linaro.org>
> ---
>  tools/perf/util/stat-display.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index a5d72f4a515c..9b7fd985a42a 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
>  	struct outstate *os = ctx;
>  	FILE *out = os->fh;
>  
> -	if (unit) {
> +	if (unit && strlen(unit)) {
>  		json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
>  		if (thresh != METRIC_THRESHOLD_UNKNOWN) {
>  			json_out(os, "\"metric-threshold\" : \"%s\"",
> -- 
> 2.34.1
>

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

Posted by Ian Rogers 3 weeks, 5 days ago

On Tue, Oct 29, 2024 at 5:42 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hello,
>
> On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
> > We decided to hide NULL metric units rather than showing it as "(null)",
> > but on hybrid systems if the process doesn't hit a PMU you get an empty
> > string metric unit instead. To make it consistent also remove empty
> > strings.
> >
> > Note that metric-threshold is already hidden in this case without this
> > change.
> >
> > Where a process only runs on cpu_core and never hits cpu_atom:
> > Before:
> >  $ perf stat -j -- true
> >  ...
> >  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
> >  {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >  ...
>
> I guess you're talking about "metric-unit", not plain "unit", right?
> Then please update the subject line to reduce the config.
>
> Ian, can you please review?

It'd be nice to see the stack trace for when metric-unit is "" as I'm
not seeing the logic in stat-shadow.c. If we know the caller than it
seems logical the unit can be passed as NULL rather than "".

Thanks,
Ian

> Thanks,
> Namhyung
>
> >
> > After:
> >  ...
> >  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
> >  {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >  ...
> >
> > Signed-off-by: James Clark <james.clark@linaro.org>
> > ---
> >  tools/perf/util/stat-display.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> > index a5d72f4a515c..9b7fd985a42a 100644
> > --- a/tools/perf/util/stat-display.c
> > +++ b/tools/perf/util/stat-display.c
> > @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
> >       struct outstate *os = ctx;
> >       FILE *out = os->fh;
> >
> > -     if (unit) {
> > +     if (unit && strlen(unit)) {
> >               json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
> >               if (thresh != METRIC_THRESHOLD_UNKNOWN) {
> >                       json_out(os, "\"metric-threshold\" : \"%s\"",
> > --
> > 2.34.1
> >

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

Posted by James Clark 3 weeks, 5 days ago


On 30/10/2024 2:45 am, Ian Rogers wrote:
> On Tue, Oct 29, 2024 at 5:42 PM Namhyung Kim <namhyung@kernel.org> wrote:
>>
>> Hello,
>>
>> On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
>>> We decided to hide NULL metric units rather than showing it as "(null)",
>>> but on hybrid systems if the process doesn't hit a PMU you get an empty
>>> string metric unit instead. To make it consistent also remove empty
>>> strings.
>>>
>>> Note that metric-threshold is already hidden in this case without this
>>> change.
>>>
>>> Where a process only runs on cpu_core and never hits cpu_atom:
>>> Before:
>>>   $ perf stat -j -- true
>>>   ...
>>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
>>>   {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>>>   ...
>>
>> I guess you're talking about "metric-unit", not plain "unit", right?
>> Then please update the subject line to reduce the config.
>>

Yep I'll update it.

>> Ian, can you please review?
> 
> It'd be nice to see the stack trace for when metric-unit is "" as I'm
> not seeing the logic in stat-shadow.c. If we know the caller than it
> seems logical the unit can be passed as NULL rather than "".
> 
> Thanks,
> Ian
> 


Here's the stack:

print_metric_json() (stat-display.c:516)
printout() (stat-display.c:912)
print_counter_aggrdata() (stat-display.c:1110)
print_counter() (stat-display.c:1224)
evlist__print_counters() (stat-display.c:1734)
print_counters() (builtin-stat.c:1016)
cmd_stat() (builtin-stat.c:2872)
run_builtin() (perf/perf.c:351)
handle_internal_command() (perf.c:404)
run_argv() (perf.c:448)
main() (perf.c:560)

The empty string is from printout():

   pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/"",
      /*val=*/0);

Changing it to NULL seems to work, so is probably a bit neater. I can do 
that if you think that makes sense?

There's another one for --metric-only that I didn't run into, but it 
could also make sense to change:

   if (config->metric_only) {
     pm(config, os, METRIC_THRESHOLD_UNKNOWN, "", "", 0);

>> Thanks,
>> Namhyung
>>
>>>
>>> After:
>>>   ...
>>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
>>>   {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>>>   ...
>>>
>>> Signed-off-by: James Clark <james.clark@linaro.org>
>>> ---
>>>   tools/perf/util/stat-display.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
>>> index a5d72f4a515c..9b7fd985a42a 100644
>>> --- a/tools/perf/util/stat-display.c
>>> +++ b/tools/perf/util/stat-display.c
>>> @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
>>>        struct outstate *os = ctx;
>>>        FILE *out = os->fh;
>>>
>>> -     if (unit) {
>>> +     if (unit && strlen(unit)) {
>>>                json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
>>>                if (thresh != METRIC_THRESHOLD_UNKNOWN) {
>>>                        json_out(os, "\"metric-threshold\" : \"%s\"",
>>> --
>>> 2.34.1
>>>

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

Posted by Ian Rogers 3 weeks, 5 days ago

On Wed, Oct 30, 2024 at 2:36 AM James Clark <james.clark@linaro.org> wrote:
>
>
>
> On 30/10/2024 2:45 am, Ian Rogers wrote:
> > On Tue, Oct 29, 2024 at 5:42 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >>
> >> Hello,
> >>
> >> On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
> >>> We decided to hide NULL metric units rather than showing it as "(null)",
> >>> but on hybrid systems if the process doesn't hit a PMU you get an empty
> >>> string metric unit instead. To make it consistent also remove empty
> >>> strings.
> >>>
> >>> Note that metric-threshold is already hidden in this case without this
> >>> change.
> >>>
> >>> Where a process only runs on cpu_core and never hits cpu_atom:
> >>> Before:
> >>>   $ perf stat -j -- true
> >>>   ...
> >>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
> >>>   {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >>>   ...
> >>
> >> I guess you're talking about "metric-unit", not plain "unit", right?
> >> Then please update the subject line to reduce the config.
> >>
>
> Yep I'll update it.
>
> >> Ian, can you please review?
> >
> > It'd be nice to see the stack trace for when metric-unit is "" as I'm
> > not seeing the logic in stat-shadow.c. If we know the caller than it
> > seems logical the unit can be passed as NULL rather than "".
> >
> > Thanks,
> > Ian
> >
>
>
> Here's the stack:
>
> print_metric_json() (stat-display.c:516)
> printout() (stat-display.c:912)
> print_counter_aggrdata() (stat-display.c:1110)
> print_counter() (stat-display.c:1224)
> evlist__print_counters() (stat-display.c:1734)
> print_counters() (builtin-stat.c:1016)
> cmd_stat() (builtin-stat.c:2872)
> run_builtin() (perf/perf.c:351)
> handle_internal_command() (perf.c:404)
> run_argv() (perf.c:448)
> main() (perf.c:560)
>
> The empty string is from printout():
>
>    pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/"",
>       /*val=*/0);
>
> Changing it to NULL seems to work, so is probably a bit neater. I can do
> that if you think that makes sense?
>
> There's another one for --metric-only that I didn't run into, but it
> could also make sense to change:
>
>    if (config->metric_only) {
>      pm(config, os, METRIC_THRESHOLD_UNKNOWN, "", "", 0);

Yeah, it looks like all the callers should be passing NULL. I feel
more comfortable doing this than ignoring the empty string which is
something a json metric may accidentally do. Could you send a patch?

Thanks,
Ian

> >> Thanks,
> >> Namhyung
> >>
> >>>
> >>> After:
> >>>   ...
> >>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
> >>>   {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >>>   ...
> >>>
> >>> Signed-off-by: James Clark <james.clark@linaro.org>
> >>> ---
> >>>   tools/perf/util/stat-display.c | 2 +-
> >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> >>> index a5d72f4a515c..9b7fd985a42a 100644
> >>> --- a/tools/perf/util/stat-display.c
> >>> +++ b/tools/perf/util/stat-display.c
> >>> @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
> >>>        struct outstate *os = ctx;
> >>>        FILE *out = os->fh;
> >>>
> >>> -     if (unit) {
> >>> +     if (unit && strlen(unit)) {
> >>>                json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
> >>>                if (thresh != METRIC_THRESHOLD_UNKNOWN) {
> >>>                        json_out(os, "\"metric-threshold\" : \"%s\"",
> >>> --
> >>> 2.34.1
> >>>
>