Re: [PATCH] perf jevents: Add dynamic IIO PCIe bandwidth metrics for Intel

[Chun-Tse Shao]

On Tue, Sep 15, 2026 at 1:35 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:
>
> On Thu, Jul 9, 2026 at 2:34 PM Chun-Tse Shao <ctshao@xxxxxxxxxx> wrote:
> >
> > + Perry for reviewing the metric.
> >
> >
> > On Thu, Jul 9, 2026 at 11:39 AM Chun-Tse Shao <ctshao@xxxxxxxxxx> wrote:
> > >
> > > Generate per-IIO-device PCIe read and write bandwidth metrics
> > > (iio_bandwidth_read_per_device_0, etc.) grouped under
> > > iio_bandwidth_per_device for Sapphire Rapids and newer architectures
> > > in intel_metrics.py.
> > >
> > > By using has_event() checks across up to 24 possible IIO stack indices,
> > > runtime perf automatically monitors only the IIO root complexes present
> > > on the system without failing on missing instances.
> > >
> > > Signed-off-by: Chun-Tse Shao <ctshao@xxxxxxxxxx>
> > > Assisted-by: Gemini:gemini-3.1-pro-preview
>
> Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>
>
> Thanks,
> Ian

Thank you Ian for reviewing the patch! I had an offline discussion
with Intel and we found:
1.  iio_bandwidth_read/write is only missing on EMR and Intel fixed
that through event updates:
lore.kernel.org/20260714204044.1952031-13-ctshao@xxxxxxxxxx
2. -A option does not work well with uncore events and I have a wip
fix for that: lore.kernel.org/20260811230518.3360-2-ctshao@xxxxxxxxxx

The patch is no longer necessary.

-CT

>
> > > ---
> > >  tools/perf/pmu-events/intel_metrics.py | 52 ++++++++++++++++++++++++++
> > >  1 file changed, 52 insertions(+)
> > >
> > > diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
> > > index bc2b920d3a0d..4f8a123a375d 100755
> > > --- a/tools/perf/pmu-events/intel_metrics.py
> > > +++ b/tools/perf/pmu-events/intel_metrics.py
> > > @@ -1132,6 +1132,57 @@ def UncoreUpiBw() -> Optional[MetricGroup]:
> > >      ], description="UPI Bandwidth")
> > >
> > >
> > > +def UncoreIioBw() -> Optional[MetricGroup]:
> > > +    if _args.model not in [
> > > +        "sapphirerapids",
> > > +        "emeraldrapids",
> > > +        "graniterapids",
> > > +        "sierraforest",
> > > +        "clearwaterforest",
> > > +    ]:
> > > +      return None
> > > +
> > > +    # On multi-socket x86 servers, there can be multiple IIO stacks per socket.
> > > +    # We generate metrics up to index 23 with has_event check so runtime perf
> > > +    # only measures the IIO instances present on the system.
> > > +    max_iios = 24
> > > +    metrics = []
> > > +    scale = 4 / 1_000_000
> > > +    for i in range(max_iios):
> > > +      rd_event = Event(
> > > +          f"uncore_iio_{i}/UNC_IIO_DATA_REQ_OF_CPU.MEM_READ.ALL_PARTS/"
> > > +      )
> > > +      wr_event = Event(
> > > +          f"uncore_iio_{i}/UNC_IIO_DATA_REQ_OF_CPU.MEM_WRITE.ALL_PARTS/"
> > > +      )
> > > +      rd_bw = Select(d_ratio(rd_event, interval_sec), has_event(rd_event), 0)
> > > +      wr_bw = Select(d_ratio(wr_event, interval_sec), has_event(wr_event), 0)
> > > +      metrics.append(
> > > +          MetricGroup(
> > > +              f"iio_bandwidth_per_device_iio{i}",
> > > +              [
> > > +                  Metric(
> > > +                      f"iio_bandwidth_read_per_device_{i}",
> > > +                      f"IIO {i} read bandwidth",
> > > +                      rd_bw,
> > > +                      f"{scale}MB/s",
> > > +                  ),
> > > +                  Metric(
> > > +                      f"iio_bandwidth_write_per_device_{i}",
> > > +                      f"IIO {i} write bandwidth",
> > > +                      wr_bw,
> > > +                      f"{scale}MB/s",
> > > +                  ),
> > > +              ],
> > > +          )
> > > +      )
> > > +    return MetricGroup(
> > > +        "iio_bandwidth_per_device",
> > > +        metrics,
> > > +        description="IIO Read/Write Bandwidth per root complex",
> > > +    )
> > > +
> > > +
> > >  def main() -> None:
> > >      global _args
> > >
> > > @@ -1179,6 +1230,7 @@ def main() -> None:
> > >          UncoreMemBw(),
> > >          UncoreMemSat(),
> > >          UncoreUpiBw(),
> > > +        UncoreIioBw(),
> > >      ])
> > >
> > >      if _args.metricgroups:
> > > --
> > > 2.55.0.795.g602f6c329a-goog
> > >