[PATCH v1 1/2] perf pmu: Make pmu_alias_terms weak again

[PATCH v1 1/2] perf pmu: Make pmu_alias_terms weak again

[Ian Rogers]

The terms for a json event should be weak so they don't override
command line options.

Fixes: 84bae3af20d0 ("perf pmu: Don't eagerly parse event terms")
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/pmu.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index d597263fab4f..f14f2a12d061 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -802,6 +802,7 @@ static int pmu_aliases_parse_eager(struct perf_pmu *pmu, int sysfs_fd)
 static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms)
 {
 	struct parse_events_terms alias_terms;
+	struct parse_events_term *term;
 	int ret;
 
 	parse_events_terms__init(&alias_terms);
@@ -812,6 +813,13 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms
 		parse_events_terms__exit(&alias_terms);
 		return ret;
 	}
+	list_for_each_entry(term, &alias_terms.terms, list) {
+		/*
+		 * Weak terms don't override command line options,
+		 * which we don't want for implicit terms in aliases.
+		 */
+		term->weak = true;
+	}
 	list_splice_init(&alias_terms.terms, terms);
 	parse_events_terms__exit(&alias_terms);
 	return 0;
-- 
2.51.1.851.g4ebd6896fd-goog

[PATCH v1 2/2] perf test: Add test that command line period overrides sysfs/json values

[Ian Rogers]

The behavior of weak terms is subtle, add a test that they aren't
accidentally broken.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/shell/record_weak_term.sh | 25 ++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100755 tools/perf/tests/shell/record_weak_term.sh

diff --git a/tools/perf/tests/shell/record_weak_term.sh b/tools/perf/tests/shell/record_weak_term.sh
new file mode 100755
index 000000000000..7b747b383796
--- /dev/null
+++ b/tools/perf/tests/shell/record_weak_term.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+# record weak terms
+# SPDX-License-Identifier: GPL-2.0
+# Test that command line options override weak terms from sysfs or inbuilt json.
+set -e
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/setup_python.sh
+. "${shelldir}"/lib/setup_python.sh
+
+
+event=$(perf list --json | $PYTHON -c "import json,sys; next((print(e['EventName']) for e in json.load(sys.stdin) if e.get('Encoding') and 'period=' in e.get('Encoding')))")
+if [[ "$?" != "0" ]]
+then
+  echo "No sysfs/json events with inbuilt period."
+  exit 2
+fi
+
+if ! perf record -c 1000 -vv -e "$event" -o /dev/null true 2>&1 | \
+  grep -q -F '{ sample_period, sample_freq }   1000'
+then
+  echo "Unexpected verbose output and sample period"
+  exit 1
+fi
+exit 0
-- 
2.51.1.851.g4ebd6896fd-goog

Re: [PATCH v1 1/2] perf pmu: Make pmu_alias_terms weak again

[Namhyung Kim]

Hi Ian,

On Wed, Oct 29, 2025 at 03:26:37PM -0700, Ian Rogers wrote:
> The terms for a json event should be weak so they don't override
> command line options.

Can you please give an example command line and the error?

Thanks,
Namhyung

> 
> Fixes: 84bae3af20d0 ("perf pmu: Don't eagerly parse event terms")
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/pmu.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index d597263fab4f..f14f2a12d061 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -802,6 +802,7 @@ static int pmu_aliases_parse_eager(struct perf_pmu *pmu, int sysfs_fd)
>  static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms)
>  {
>  	struct parse_events_terms alias_terms;
> +	struct parse_events_term *term;
>  	int ret;
>  
>  	parse_events_terms__init(&alias_terms);
> @@ -812,6 +813,13 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms
>  		parse_events_terms__exit(&alias_terms);
>  		return ret;
>  	}
> +	list_for_each_entry(term, &alias_terms.terms, list) {
> +		/*
> +		 * Weak terms don't override command line options,
> +		 * which we don't want for implicit terms in aliases.
> +		 */
> +		term->weak = true;
> +	}
>  	list_splice_init(&alias_terms.terms, terms);
>  	parse_events_terms__exit(&alias_terms);
>  	return 0;
> -- 
> 2.51.1.851.g4ebd6896fd-goog
> 

Re: [PATCH v1 1/2] perf pmu: Make pmu_alias_terms weak again

[Ian Rogers]

On Wed, Oct 29, 2025 at 10:47 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hi Ian,
>
> On Wed, Oct 29, 2025 at 03:26:37PM -0700, Ian Rogers wrote:
> > The terms for a json event should be weak so they don't override
> > command line options.
>
> Can you please give an example command line and the error?

Sure, it is also covered in the test.

Before:
```
$ perf record -vv -c 1000 -e uops_issued.any -o /dev/null true 2>&1
|grep "{ sample_period, sample_freq }"
 { sample_period, sample_freq }   200003
 { sample_period, sample_freq }   2000003
 { sample_period, sample_freq }   1000
```

After:
```
$ perf record -vv -c 1000 -e uops_issued.any -o /dev/null true 2>&1
|grep "{ sample_period, sample_freq }"
 { sample_period, sample_freq }   1000
 { sample_period, sample_freq }   1000
 { sample_period, sample_freq }   1000
```

Thanks,
Ian

> Thanks,
> Namhyung
>
> >
> > Fixes: 84bae3af20d0 ("perf pmu: Don't eagerly parse event terms")
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/util/pmu.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > index d597263fab4f..f14f2a12d061 100644
> > --- a/tools/perf/util/pmu.c
> > +++ b/tools/perf/util/pmu.c
> > @@ -802,6 +802,7 @@ static int pmu_aliases_parse_eager(struct perf_pmu *pmu, int sysfs_fd)
> >  static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms)
> >  {
> >       struct parse_events_terms alias_terms;
> > +     struct parse_events_term *term;
> >       int ret;
> >
> >       parse_events_terms__init(&alias_terms);
> > @@ -812,6 +813,13 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms
> >               parse_events_terms__exit(&alias_terms);
> >               return ret;
> >       }
> > +     list_for_each_entry(term, &alias_terms.terms, list) {
> > +             /*
> > +              * Weak terms don't override command line options,
> > +              * which we don't want for implicit terms in aliases.
> > +              */
> > +             term->weak = true;
> > +     }
> >       list_splice_init(&alias_terms.terms, terms);
> >       parse_events_terms__exit(&alias_terms);
> >       return 0;
> > --
> > 2.51.1.851.g4ebd6896fd-goog
> >

Re: [PATCH v1 1/2] perf pmu: Make pmu_alias_terms weak again

[Namhyung Kim]

On Thu, Oct 30, 2025 at 08:08:02AM -0700, Ian Rogers wrote:
> On Wed, Oct 29, 2025 at 10:47 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > Hi Ian,
> >
> > On Wed, Oct 29, 2025 at 03:26:37PM -0700, Ian Rogers wrote:
> > > The terms for a json event should be weak so they don't override
> > > command line options.
> >
> > Can you please give an example command line and the error?
> 
> Sure, it is also covered in the test.

Yep, but lazy maintainers want to see it in the commit message. :)

> 
> Before:
> ```
> $ perf record -vv -c 1000 -e uops_issued.any -o /dev/null true 2>&1
> |grep "{ sample_period, sample_freq }"
>  { sample_period, sample_freq }   200003
>  { sample_period, sample_freq }   2000003
>  { sample_period, sample_freq }   1000
> ```
> 
> After:
> ```
> $ perf record -vv -c 1000 -e uops_issued.any -o /dev/null true 2>&1
> |grep "{ sample_period, sample_freq }"
>  { sample_period, sample_freq }   1000
>  { sample_period, sample_freq }   1000
>  { sample_period, sample_freq }   1000
> ```

Thanks, it ignored command line options.  I can see the default period
is in the JSON description.

  $ perf list -j | grep -C 5 uops_issued.any
  	"Encoding": "cpu/event=0xb1,period=2000003,umask=0x10/"
  },
  {
  	"Unit": "cpu",
  	"Topic": "pipeline",
  	"EventName": "uops_issued.any",
  	"EventType": "Kernel PMU event",
  	"BriefDescription": "Uops that RAT issues to RS",
  	"PublicDescription": "Counts the number of uops that the Resource Allocation Table (RAT) issues to the Reservation Station (RS)",
  	"Encoding": "cpu/event=0xe,period=2000003,umask=1/"
  },

It'd be great if you could include this kind of info in the commit log
so that others can understand the problem clearly and test the patch
easily.

Thanks,
Namhyung

> > >
> > > Fixes: 84bae3af20d0 ("perf pmu: Don't eagerly parse event terms")
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/perf/util/pmu.c | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > >
> > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > > index d597263fab4f..f14f2a12d061 100644
> > > --- a/tools/perf/util/pmu.c
> > > +++ b/tools/perf/util/pmu.c
> > > @@ -802,6 +802,7 @@ static int pmu_aliases_parse_eager(struct perf_pmu *pmu, int sysfs_fd)
> > >  static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms)
> > >  {
> > >       struct parse_events_terms alias_terms;
> > > +     struct parse_events_term *term;
> > >       int ret;
> > >
> > >       parse_events_terms__init(&alias_terms);
> > > @@ -812,6 +813,13 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias, struct list_head *terms
> > >               parse_events_terms__exit(&alias_terms);
> > >               return ret;
> > >       }
> > > +     list_for_each_entry(term, &alias_terms.terms, list) {
> > > +             /*
> > > +              * Weak terms don't override command line options,
> > > +              * which we don't want for implicit terms in aliases.
> > > +              */
> > > +             term->weak = true;
> > > +     }
> > >       list_splice_init(&alias_terms.terms, terms);
> > >       parse_events_terms__exit(&alias_terms);
> > >       return 0;
> > > --
> > > 2.51.1.851.g4ebd6896fd-goog
> > >

Re: [PATCH v1 2/2] perf test: Add test that command line period overrides sysfs/json values

[Namhyung Kim]

On Wed, Oct 29, 2025 at 03:26:38PM -0700, Ian Rogers wrote:
> The behavior of weak terms is subtle, add a test that they aren't
> accidentally broken.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/tests/shell/record_weak_term.sh | 25 ++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>  create mode 100755 tools/perf/tests/shell/record_weak_term.sh
> 
> diff --git a/tools/perf/tests/shell/record_weak_term.sh b/tools/perf/tests/shell/record_weak_term.sh
> new file mode 100755
> index 000000000000..7b747b383796
> --- /dev/null
> +++ b/tools/perf/tests/shell/record_weak_term.sh
> @@ -0,0 +1,25 @@
> +#!/bin/bash
> +# record weak terms
> +# SPDX-License-Identifier: GPL-2.0
> +# Test that command line options override weak terms from sysfs or inbuilt json.
> +set -e
> +
> +shelldir=$(dirname "$0")
> +# shellcheck source=lib/setup_python.sh
> +. "${shelldir}"/lib/setup_python.sh
> +
> +
> +event=$(perf list --json | $PYTHON -c "import json,sys; next((print(e['EventName']) for e in json.load(sys.stdin) if e.get('Encoding') and 'period=' in e.get('Encoding')))")

This line is too long and needs some explanation like what's like the
original text and what it does.

Thanks,
Namhyung


> +if [[ "$?" != "0" ]]
> +then
> +  echo "No sysfs/json events with inbuilt period."
> +  exit 2
> +fi
> +
> +if ! perf record -c 1000 -vv -e "$event" -o /dev/null true 2>&1 | \
> +  grep -q -F '{ sample_period, sample_freq }   1000'
> +then
> +  echo "Unexpected verbose output and sample period"
> +  exit 1
> +fi
> +exit 0
> -- 
> 2.51.1.851.g4ebd6896fd-goog
> 

Re: [PATCH v1 2/2] perf test: Add test that command line period overrides sysfs/json values

[Ian Rogers]

On Mon, Nov 3, 2025 at 7:37 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Wed, Oct 29, 2025 at 03:26:38PM -0700, Ian Rogers wrote:
> > The behavior of weak terms is subtle, add a test that they aren't
> > accidentally broken.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/tests/shell/record_weak_term.sh | 25 ++++++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >  create mode 100755 tools/perf/tests/shell/record_weak_term.sh
> >
> > diff --git a/tools/perf/tests/shell/record_weak_term.sh b/tools/perf/tests/shell/record_weak_term.sh
> > new file mode 100755
> > index 000000000000..7b747b383796
> > --- /dev/null
> > +++ b/tools/perf/tests/shell/record_weak_term.sh
> > @@ -0,0 +1,25 @@
> > +#!/bin/bash
> > +# record weak terms
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Test that command line options override weak terms from sysfs or inbuilt json.
> > +set -e
> > +
> > +shelldir=$(dirname "$0")
> > +# shellcheck source=lib/setup_python.sh
> > +. "${shelldir}"/lib/setup_python.sh
> > +
> > +
> > +event=$(perf list --json | $PYTHON -c "import json,sys; next((print(e['EventName']) for e in json.load(sys.stdin) if e.get('Encoding') and 'period=' in e.get('Encoding')))")
>
> This line is too long

Is there a good way to split such a line?

> and needs some explanation like what's like the original text and what it does.

I thought that was covered in the "if" below:

> > +if [[ "$?" != "0" ]]
> > +then
> > +  echo "No sysfs/json events with inbuilt period."
> > +  exit 2
> > +fi

Thanks,
Ian

> > +
> > +if ! perf record -c 1000 -vv -e "$event" -o /dev/null true 2>&1 | \
> > +  grep -q -F '{ sample_period, sample_freq }   1000'
> > +then
> > +  echo "Unexpected verbose output and sample period"
> > +  exit 1
> > +fi
> > +exit 0
> > --
> > 2.51.1.851.g4ebd6896fd-goog
> >

Re: [PATCH v1 2/2] perf test: Add test that command line period overrides sysfs/json values

[Namhyung Kim]

On Mon, Nov 03, 2025 at 09:22:00PM -0800, Ian Rogers wrote:
> On Mon, Nov 3, 2025 at 7:37 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > On Wed, Oct 29, 2025 at 03:26:38PM -0700, Ian Rogers wrote:
> > > The behavior of weak terms is subtle, add a test that they aren't
> > > accidentally broken.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > >  tools/perf/tests/shell/record_weak_term.sh | 25 ++++++++++++++++++++++
> > >  1 file changed, 25 insertions(+)
> > >  create mode 100755 tools/perf/tests/shell/record_weak_term.sh
> > >
> > > diff --git a/tools/perf/tests/shell/record_weak_term.sh b/tools/perf/tests/shell/record_weak_term.sh
> > > new file mode 100755
> > > index 000000000000..7b747b383796
> > > --- /dev/null
> > > +++ b/tools/perf/tests/shell/record_weak_term.sh
> > > @@ -0,0 +1,25 @@
> > > +#!/bin/bash
> > > +# record weak terms
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +# Test that command line options override weak terms from sysfs or inbuilt json.
> > > +set -e
> > > +
> > > +shelldir=$(dirname "$0")
> > > +# shellcheck source=lib/setup_python.sh
> > > +. "${shelldir}"/lib/setup_python.sh
> > > +
> > > +
> > > +event=$(perf list --json | $PYTHON -c "import json,sys; next((print(e['EventName']) for e in json.load(sys.stdin) if e.get('Encoding') and 'period=' in e.get('Encoding')))")
> >
> > This line is too long
> 
> Is there a good way to split such a line?

Wouldn't this work?

  event=$(perf list --json | python -c '
  import sys, json
  for e in json.load(sys.stdin):
    if e.get("Encoding") and "period=" in e.get("Encoding"):
      print(e["EventName"])')

> 
> > and needs some explanation like what's like the original text and what it does.
> 
> I thought that was covered in the "if" below:

Yeah, but I think it's useful to have an example JSON text.

Thanks,
Namhyung

> 
> > > +if [[ "$?" != "0" ]]
> > > +then
> > > +  echo "No sysfs/json events with inbuilt period."
> > > +  exit 2
> > > +fi
> 
> Thanks,
> Ian
> 
> > > +
> > > +if ! perf record -c 1000 -vv -e "$event" -o /dev/null true 2>&1 | \
> > > +  grep -q -F '{ sample_period, sample_freq }   1000'
> > > +then
> > > +  echo "Unexpected verbose output and sample period"
> > > +  exit 1
> > > +fi
> > > +exit 0
> > > --
> > > 2.51.1.851.g4ebd6896fd-goog
> > >